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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 (
    20749, 20750, 20751, 20752, 20753, 20754, 
    20755, 20756, 20757, 20758, 20759, 
    20760, 20761, 20762, 20763, 20764
  ) 
  AND cscart_product_review_prepared_data.storefront_id = 0

Query time 0.00015

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 (20749,20750,20751,20752,20753,20754,20755,20756,20757,20758,20759,20760,20761,20762,20763,20764)"
    }
  }
}