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 (
    338, 335, 334, 333, 332, 331, 330, 321, 
    320, 319, 318, 317, 316, 315, 314, 313, 
    312, 311, 310, 309, 308, 307, 306, 305, 
    304, 303, 302, 300, 298, 297, 296, 295
  ) 
  AND cscart_product_review_prepared_data.storefront_id = 0

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_product_review_prepared_data",
          "access_type": "ALL",
          "possible_keys": ["PRIMARY"],
          "rows": 3,
          "filtered": 100,
          "attached_condition": "cscart_product_review_prepared_data.storefront_id = 0 and cscart_product_review_prepared_data.product_id in (338,335,334,333,332,331,330,321,320,319,318,317,316,315,314,313,312,311,310,309,308,307,306,305,304,303,302,300,298,297,296,295)"
        }
      }
    ]
  }
}