SELECT 
  cscart_product_prices.product_id, 
  MIN(
    IF(
      cscart_product_prices.percentage_discount = 0, 
      cscart_product_prices.price, 
      cscart_product_prices.price - (
        cscart_product_prices.price * cscart_product_prices.percentage_discount
      )/ 100
    )
  ) AS price 
FROM 
  cscart_product_prices 
WHERE 
  cscart_product_prices.product_id IN (
    95922, 95921, 95839, 94774, 96891, 96733, 
    95876, 96757, 96756, 96755, 96754, 
    96753, 96752, 96751, 96750, 96749, 
    96748, 96743, 96715, 96711
  ) 
  AND cscart_product_prices.lower_limit = 1 
  AND cscart_product_prices.usergroup_id IN (0, 1) 
GROUP BY 
  cscart_product_prices.product_id

Query time 0.00058

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE cscart_product_prices range usergroup,product_id,lower_limit,usergroup_id usergroup 9 40 Using where

Result

product_id price
94774 1.69000000
95839 1.69000000
95876 1.69000000
95921 1.69000000
95922 1.69000000
96711 1.69000000
96715 1.69000000
96733 1.69000000
96743 1.69000000
96748 1.69000000
96749 1.69000000
96750 1.69000000
96751 1.69000000
96752 1.69000000
96753 1.69000000
96754 1.69000000
96755 1.69000000
96756 1.69000000
96757 1.69000000
96891 1.69000000