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 (341, 346, 351, 286, 287, 288) 
  AND cscart_product_review_prepared_data.storefront_id = 0

Query time 0.00032

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE cscart_product_review_prepared_data range PRIMARY PRIMARY 7 6 Using index condition

Result

product_id average_rating reviews_count
286 4.67 3
287 4.67 3
288 4.67 3
341 4.00 3
346 4.00 3
351 4.00 3