Sandbox

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 (
    6420, 6421, 2823, 2824, 2825, 2826, 6408, 
    6409, 6410, 6411, 6412, 2827
  ) 
  AND cscart_product_review_prepared_data.storefront_id = 0

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "Impossible WHERE noticed after reading const tables"
  }
}