SELECT 
  average_rating 
FROM 
  cscart_company_product_review_prepared_data 
WHERE 
  company_id = 635

Query time 0.78201

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "<derived2>",
          "access_type": "ALL",
          "rows": 56246,
          "filtered": 100,
          "attached_condition": "cscart_company_product_review_prepared_data.company_id = 635",
          "materialized": {
            "query_block": {
              "select_id": 2,
              "nested_loop": [
                {
                  "table": {
                    "table_name": "PRD",
                    "access_type": "ALL",
                    "possible_keys": ["PRIMARY"],
                    "rows": 56246,
                    "filtered": 100
                  }
                },
                {
                  "table": {
                    "table_name": "P",
                    "access_type": "eq_ref",
                    "possible_keys": ["PRIMARY"],
                    "key": "PRIMARY",
                    "key_length": "3",
                    "used_key_parts": ["product_id"],
                    "ref": ["dev_db.PRD.product_id"],
                    "rows": 1,
                    "filtered": 100,
                    "attached_condition": "P.company_id = 635"
                  }
                }
              ]
            }
          }
        }
      }
    ]
  }
}