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 (
    18508, 18520, 19947, 18481, 19942, 19936, 
    19937, 19938, 19939, 19940, 19941
  ) 
  AND cscart_product_review_prepared_data.storefront_id = 0

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.01172581,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_product_review_prepared_data",
          "access_type": "range",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "7",
          "used_key_parts": ["product_id", "storefront_id"],
          "loops": 1,
          "rows": 11,
          "cost": 0.01172581,
          "filtered": 100,
          "attached_condition": "cscart_product_review_prepared_data.storefront_id = 0 and cscart_product_review_prepared_data.product_id in (18508,18520,19947,18481,19942,19936,19937,19938,19939,19940,19941)"
        }
      }
    ]
  }
}