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SELECT 
  cscart_product_review_prepared_data.product_id AS product_id, 
  cscart_product_review_prepared_data.average_rating AS average_rating, 
  cscart_product_review_prepared_data.reviews_count AS reviews_count 
FROM 
  cscart_product_review_prepared_data 
WHERE 
  cscart_product_review_prepared_data.product_id IN (
    20189, 20190, 20191, 20192, 20193, 20194, 
    20195, 20196, 20197, 20198, 20199, 
    20200, 20201, 20202, 20203, 20204
  ) 
  AND cscart_product_review_prepared_data.storefront_id = 0

Query time 0.00013

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_product_review_prepared_data",
      "access_type": "ALL",
      "possible_keys": ["PRIMARY"],
      "rows": 5,
      "filtered": 100,
      "attached_condition": "cscart_product_review_prepared_data.storefront_id = 0 and cscart_product_review_prepared_data.product_id in (20189,20190,20191,20192,20193,20194,20195,20196,20197,20198,20199,20200,20201,20202,20203,20204)"
    }
  }
}