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 (
    94716, 94710, 94709, 94301, 94300, 94058, 
    93757, 94188, 93728, 93727, 93726, 
    93725, 93724, 93723, 93722, 93721, 
    93720, 93719, 93718, 93717
  ) 
  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 0.00090

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
93717 1.69000000
93718 1.69000000
93719 1.69000000
93720 1.69000000
93721 1.69000000
93722 1.69000000
93723 1.69000000
93724 1.69000000
93725 1.69000000
93726 1.69000000
93727 1.69000000
93728 1.69000000
93757 1.69000000
94058 1.69000000
94188 1.69000000
94300 1.69000000
94301 1.69000000
94709 1.69000000
94710 1.69000000
94716 1.69000000