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 (
    110125, 110123, 110441, 110065, 110387, 
    110143, 110062, 110060, 110058, 110057, 
    110056, 110055, 110157, 110118, 110030, 
    110029, 109951, 109950, 109948, 109947
  ) 
  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 0.00048

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
109947 1.69000000
109948 1.69000000
109950 1.69000000
109951 1.69000000
110029 1.69000000
110030 1.69000000
110055 1.69000000
110056 1.69000000
110057 1.69000000
110058 1.69000000
110060 1.69000000
110062 1.69000000
110065 1.69000000
110118 1.69000000
110123 1.69000000
110125 1.69000000
110143 1.69000000
110157 1.69000000
110387 1.69000000
110441 1.69000000