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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 (
    20461, 20462, 20463, 20464, 20465, 20466, 
    20467, 20468, 20469, 20470, 20471, 
    20472, 20473, 20474, 20475, 20476
  ) 
  AND cscart_product_review_prepared_data.storefront_id = 0

Query time 0.00019

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 (20461,20462,20463,20464,20465,20466,20467,20468,20469,20470,20471,20472,20473,20474,20475,20476)"
    }
  }
}