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 (
    97123, 97122, 109027, 109026, 108917, 
    108999, 108998, 108975, 109046, 108960, 
    108877, 108920, 110746, 110725, 97093, 
    97092, 113549, 122783, 125264, 97127
  ) 
  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 0.00069

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
97092 1.69000000
97093 1.69000000
97122 1.69000000
97123 1.69000000
97127 1.69000000
108877 1.69000000
108917 1.69000000
108920 1.69000000
108960 1.69000000
108975 1.69000000
108998 1.69000000
108999 1.69000000
109026 1.69000000
109027 1.69000000
109046 1.69000000
110725 1.69000000
110746 1.69000000
113549 1.69000000
122783 1.69000000
125264 1.69000000