SELECT 
  company_descriptions.*, 
  companies.*, 
  cscart_vendor_plan_descriptions.plan, 
  cscart_seo_names.name as seo_name, 
  cscart_seo_names.path as seo_path, 
  CAST(
    AVG(`prd`.`average_rating`) AS DECIMAL(10, 2)
  ) AS average_rating, 
  prd.reviews_count product_reviews_count 
FROM 
  cscart_companies AS companies 
  LEFT JOIN cscart_company_descriptions AS company_descriptions ON company_descriptions.company_id = companies.company_id 
  AND company_descriptions.lang_code = 'en' 
  LEFT JOIN cscart_vendor_plan_descriptions ON companies.plan_id = cscart_vendor_plan_descriptions.plan_id 
  AND cscart_vendor_plan_descriptions.lang_code = 'en' 
  LEFT JOIN cscart_seo_names ON cscart_seo_names.object_id = 800 
  AND cscart_seo_names.type = 'm' 
  AND cscart_seo_names.dispatch = '' 
  AND cscart_seo_names.lang_code = 'en' 
  LEFT JOIN cscart_products p ON p.company_id = companies.company_id 
  LEFT JOIN cscart_product_review_prepared_data prd ON p.product_id = prd.product_id 
WHERE 
  companies.company_id = 800

Query time 0.08494

JSON explain

{
  "query_block": {
    "select_id": 1,
    "const_condition": "1",
    "nested_loop": [
      {
        "table": {
          "table_name": "companies",
          "access_type": "const",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "4",
          "used_key_parts": ["company_id"],
          "ref": ["const"],
          "rows": 1,
          "filtered": 100
        }
      },
      {
        "table": {
          "table_name": "company_descriptions",
          "access_type": "const",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "10",
          "used_key_parts": ["company_id", "lang_code"],
          "ref": ["const", "const"],
          "rows": 1,
          "filtered": 100
        }
      },
      {
        "table": {
          "table_name": "cscart_vendor_plan_descriptions",
          "access_type": "const",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "10",
          "used_key_parts": ["plan_id", "lang_code"],
          "ref": ["const", "const"],
          "rows": 1,
          "filtered": 100
        }
      },
      {
        "table": {
          "table_name": "cscart_seo_names",
          "access_type": "ref",
          "possible_keys": ["PRIMARY", "dispatch"],
          "key": "PRIMARY",
          "key_length": "206",
          "used_key_parts": ["object_id", "type", "dispatch", "lang_code"],
          "ref": ["const", "const", "const", "const"],
          "rows": 1,
          "filtered": 100,
          "attached_condition": "trigcond(cscart_seo_names.`type` = 'm' and cscart_seo_names.dispatch = '' and cscart_seo_names.lang_code = 'en')"
        }
      },
      {
        "block-nl-join": {
          "table": {
            "table_name": "p",
            "access_type": "ALL",
            "rows": 25270,
            "filtered": 100,
            "attached_condition": "p.company_id = 800"
          },
          "buffer_type": "flat",
          "buffer_size": "18Kb",
          "join_type": "BNL",
          "attached_condition": "trigcond(p.company_id = 800)"
        }
      },
      {
        "table": {
          "table_name": "prd",
          "access_type": "ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["product_id"],
          "ref": ["dev_db.p.product_id"],
          "rows": 562,
          "filtered": 100,
          "attached_condition": "trigcond(trigcond(p.product_id is not null))"
        }
      }
    ]
  }
}