SELECT 
  SQL_CALC_FOUND_ROWS products.product_id, 
  products.amount, 
  descr1.product as product, 
  companies.company as company_name, 
  variation_group_products.group_id AS variation_group_id, 
  products.product_type, 
  products.parent_product_id, 
  cscart_product_review_prepared_data.average_rating average_rating, 
  cscart_product_review_prepared_data.reviews_count product_reviews_count 
FROM 
  cscart_products as products 
  LEFT JOIN cscart_product_descriptions as descr1 ON descr1.product_id = products.product_id 
  AND descr1.lang_code = 'en' 
  LEFT JOIN cscart_companies AS companies ON companies.company_id = products.company_id 
  INNER JOIN cscart_products_categories as products_categories ON products_categories.product_id = products.product_id 
  INNER JOIN cscart_categories ON cscart_categories.category_id = products_categories.category_id 
  INNER JOIN cscart_product_variation_group_products AS variation_group_products ON variation_group_products.product_id = products.product_id 
  LEFT JOIN cscart_product_review_prepared_data ON cscart_product_review_prepared_data.product_id = products.product_id 
  AND cscart_product_review_prepared_data.storefront_id = 0 
WHERE 
  1 
  AND companies.status IN ('A') 
  AND (
    products.usergroup_ids = '' 
    OR FIND_IN_SET(0, products.usergroup_ids) 
    OR FIND_IN_SET(1, products.usergroup_ids)
  ) 
  AND products.status IN ('A') 
  AND variation_group_products.group_id IN (
    15816, 15813, 15814, 15821, 15820, 15818
  ) 
GROUP BY 
  products.product_id 
ORDER BY 
  NULL asc

Query time 0.00531

JSON explain

{
  "query_block": {
    "select_id": 1,
    "temporary_table": {
      "nested_loop": [
        {
          "table": {
            "table_name": "variation_group_products",
            "access_type": "range",
            "possible_keys": ["PRIMARY", "idx_group_id"],
            "key": "idx_group_id",
            "key_length": "3",
            "used_key_parts": ["group_id"],
            "rows": 18,
            "filtered": 100,
            "index_condition": "variation_group_products.group_id in (15816,15813,15814,15821,15820,15818)"
          }
        },
        {
          "table": {
            "table_name": "products",
            "access_type": "eq_ref",
            "possible_keys": ["PRIMARY", "status"],
            "key": "PRIMARY",
            "key_length": "3",
            "used_key_parts": ["product_id"],
            "ref": ["dev_db.variation_group_products.product_id"],
            "rows": 1,
            "filtered": 51.89157104,
            "attached_condition": "(products.usergroup_ids = '' or find_in_set(0,products.usergroup_ids) or find_in_set(1,products.usergroup_ids)) and products.`status` = 'A'"
          }
        },
        {
          "table": {
            "table_name": "companies",
            "access_type": "eq_ref",
            "possible_keys": ["PRIMARY"],
            "key": "PRIMARY",
            "key_length": "4",
            "used_key_parts": ["company_id"],
            "ref": ["dev_db.products.company_id"],
            "rows": 1,
            "filtered": 100,
            "attached_condition": "companies.`status` = 'A'"
          }
        },
        {
          "table": {
            "table_name": "descr1",
            "access_type": "eq_ref",
            "possible_keys": ["PRIMARY", "product_id"],
            "key": "PRIMARY",
            "key_length": "11",
            "used_key_parts": ["product_id", "lang_code"],
            "ref": ["dev_db.variation_group_products.product_id", "const"],
            "rows": 1,
            "filtered": 100,
            "attached_condition": "trigcond(descr1.lang_code = 'en')"
          }
        },
        {
          "table": {
            "table_name": "cscart_product_review_prepared_data",
            "access_type": "eq_ref",
            "possible_keys": ["PRIMARY"],
            "key": "PRIMARY",
            "key_length": "7",
            "used_key_parts": ["product_id", "storefront_id"],
            "ref": ["dev_db.variation_group_products.product_id", "const"],
            "rows": 1,
            "filtered": 100
          }
        },
        {
          "table": {
            "table_name": "products_categories",
            "access_type": "ref",
            "possible_keys": ["PRIMARY", "pt"],
            "key": "pt",
            "key_length": "3",
            "used_key_parts": ["product_id"],
            "ref": ["dev_db.variation_group_products.product_id"],
            "rows": 1,
            "filtered": 100
          }
        },
        {
          "table": {
            "table_name": "cscart_categories",
            "access_type": "eq_ref",
            "possible_keys": ["PRIMARY", "p_category_id"],
            "key": "PRIMARY",
            "key_length": "3",
            "used_key_parts": ["category_id"],
            "ref": ["dev_db.products_categories.category_id"],
            "rows": 1,
            "filtered": 100,
            "using_index": true
          }
        }
      ]
    }
  }
}