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 (
    95338, 95301, 95193, 95192, 94875, 94822, 
    94657, 94656, 93317, 95297, 95296, 
    94543, 94800, 95005, 92915, 95267, 
    95266, 95265, 95263, 95257
  ) 
  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 0.00055

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
92915 1.69000000
93317 1.69000000
94543 1.69000000
94656 1.69000000
94657 1.69000000
94800 1.69000000
94822 1.69000000
94875 1.69000000
95005 1.69000000
95192 1.69000000
95193 1.69000000
95257 1.69000000
95263 1.69000000
95265 1.69000000
95266 1.69000000
95267 1.69000000
95296 1.69000000
95297 1.69000000
95301 1.69000000
95338 1.69000000