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 (
    110277, 110260, 110259, 110253, 111636, 
    110353, 110352, 110347, 110225, 110224, 
    110355, 110192, 110188, 110187, 110344, 
    110321, 110251, 110134, 110128, 110127
  ) 
  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 0.00057

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
110127 1.69000000
110128 1.69000000
110134 1.69000000
110187 1.69000000
110188 1.69000000
110192 1.69000000
110224 1.69000000
110225 1.69000000
110251 1.69000000
110253 1.69000000
110259 1.69000000
110260 1.69000000
110277 1.69000000
110321 1.69000000
110344 1.69000000
110347 1.69000000
110352 1.69000000
110353 1.69000000
110355 1.69000000
111636 1.69000000