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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 (
    5939, 6012, 6013, 6014, 6015, 6016, 6017, 
    6018, 6019, 6020, 6196, 6197
  ) 
  AND cscart_product_review_prepared_data.storefront_id = 0

Query time 0.00025

JSON explain

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