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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 (
    8326, 8328, 8333, 8342, 8343, 8344, 8345, 
    8355, 8356, 8362, 8365, 8366, 8367, 
    8368, 8370, 8371
  ) 
  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 (8326,8328,8333,8342,8343,8344,8345,8355,8356,8362,8365,8366,8367,8368,8370,8371)"
    }
  }
}