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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 (
    21604, 21607, 21606, 21602, 21599, 21617, 
    21616, 21611, 21595, 21597, 21578, 
    21596, 21577, 21561, 21562, 21563, 
    21610, 21615, 21601, 21598, 21591, 
    21592, 21593, 21594
  ) 
  AND cscart_product_review_prepared_data.storefront_id = 0

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}