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 (
    20925, 20926, 20927, 20928, 20929, 20930, 
    20931, 20932, 20933, 20934, 20935, 
    20936, 20937, 20938, 20939, 20940
  ) 
  AND cscart_product_review_prepared_data.storefront_id = 0

Query time 0.00025

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 (20925,20926,20927,20928,20929,20930,20931,20932,20933,20934,20935,20936,20937,20938,20939,20940)"
    }
  }
}