SELECT 
  cscart_bm_snapping.grid_id as grid_id, 
  cscart_bm_snapping.block_id as block_id, 
  IFNULL(
    dynamic_object_content.content, 
    default_content.content
  ) as content, 
  IFNULL(
    dynamic_object_content.object_id, 
    default_content.object_id
  ) AS object_id, 
  IFNULL(
    dynamic_object_content.object_type, 
    default_content.object_type
  ) AS object_type, 
  cscart_bm_block_statuses.object_ids as object_ids, 
  cscart_bm_snapping.*, 
  cscart_bm_blocks.*, 
  cscart_bm_blocks_descriptions.* 
FROM 
  cscart_bm_snapping 
  LEFT JOIN cscart_bm_blocks ON cscart_bm_blocks.block_id = cscart_bm_snapping.block_id 
  LEFT JOIN cscart_bm_block_statuses ON cscart_bm_snapping.snapping_id = cscart_bm_block_statuses.snapping_id 
  AND cscart_bm_block_statuses.object_type LIKE '' 
  LEFT JOIN cscart_bm_blocks_descriptions ON cscart_bm_blocks.block_id = cscart_bm_blocks_descriptions.block_id 
  LEFT JOIN cscart_bm_blocks_content AS default_content ON cscart_bm_blocks.block_id = default_content.block_id 
  AND cscart_bm_blocks_descriptions.lang_code = default_content.lang_code 
  AND default_content.snapping_id = 0 
  AND default_content.object_id = 0 
  AND default_content.object_type like '' 
  LEFT JOIN cscart_bm_blocks_content AS dynamic_object_content ON cscart_bm_blocks.block_id = dynamic_object_content.block_id 
  AND cscart_bm_blocks_descriptions.lang_code = dynamic_object_content.lang_code 
  AND dynamic_object_content.object_id = 0 
  AND dynamic_object_content.object_type like '' 
WHERE 
  cscart_bm_snapping.grid_id IN (
    301, 302, 303, 304, 305, 306, 369, 329, 
    319, 320, 321, 322, 318, 362
  ) 
  AND cscart_bm_blocks_descriptions.lang_code = 'en' 
ORDER BY 
  cscart_bm_snapping.order, 
  cscart_bm_snapping.block_id

Query time 0.00283

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "read_sorted_file": {
          "filesort": {
            "sort_key": "cscart_bm_snapping.`order`, cscart_bm_snapping.block_id",
            "table": {
              "table_name": "cscart_bm_snapping",
              "access_type": "range",
              "possible_keys": ["grid_id"],
              "key": "grid_id",
              "key_length": "4",
              "used_key_parts": ["grid_id"],
              "rows": 18,
              "filtered": 100,
              "index_condition": "cscart_bm_snapping.grid_id in (301,302,303,304,305,306,369,329,319,320,321,322,318,362)"
            }
          }
        }
      },
      {
        "table": {
          "table_name": "cscart_bm_blocks",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "4",
          "used_key_parts": ["block_id"],
          "ref": ["dev_db.cscart_bm_snapping.block_id"],
          "rows": 1,
          "filtered": 100
        }
      },
      {
        "table": {
          "table_name": "cscart_bm_blocks_descriptions",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "12",
          "used_key_parts": ["block_id", "lang_code"],
          "ref": ["dev_db.cscart_bm_snapping.block_id", "const"],
          "rows": 1,
          "filtered": 100,
          "index_condition": "cscart_bm_blocks_descriptions.lang_code = 'en'"
        }
      },
      {
        "table": {
          "table_name": "cscart_bm_block_statuses",
          "access_type": "ref",
          "possible_keys": ["snapping_id"],
          "key": "snapping_id",
          "key_length": "4",
          "used_key_parts": ["snapping_id"],
          "ref": ["dev_db.cscart_bm_snapping.snapping_id"],
          "rows": 1,
          "filtered": 100,
          "attached_condition": "trigcond(cscart_bm_snapping.snapping_id = cscart_bm_block_statuses.snapping_id and cscart_bm_block_statuses.object_type like '')"
        }
      },
      {
        "table": {
          "table_name": "default_content",
          "access_type": "ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "20",
          "used_key_parts": ["block_id", "snapping_id", "lang_code", "object_id"],
          "ref": [
            "dev_db.cscart_bm_snapping.block_id",
            "const",
            "dev_db.cscart_bm_blocks_descriptions.lang_code",
            "const"
          ],
          "rows": 1,
          "filtered": 100,
          "attached_condition": "trigcond(default_content.object_type like '')"
        }
      },
      {
        "table": {
          "table_name": "dynamic_object_content",
          "access_type": "ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "4",
          "used_key_parts": ["block_id"],
          "ref": ["dev_db.cscart_bm_snapping.block_id"],
          "rows": 3,
          "filtered": 100,
          "attached_condition": "trigcond(dynamic_object_content.lang_code = cscart_bm_blocks_descriptions.lang_code and dynamic_object_content.object_id = 0 and dynamic_object_content.object_type like '')"
        }
      }
    ]
  }
}