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 (
    97173, 97172, 97030, 97023, 96557, 94775, 
    92923, 96735, 97037, 96932, 97022, 
    96993, 96992, 96991, 96986, 96933, 
    96890, 96183, 92922, 96734
  ) 
  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 0.00092

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
92922 1.69000000
92923 1.69000000
94775 1.69000000
96183 1.69000000
96557 1.69000000
96734 1.69000000
96735 1.69000000
96890 1.69000000
96932 1.69000000
96933 1.69000000
96986 1.69000000
96991 1.69000000
96992 1.69000000
96993 1.69000000
97022 1.69000000
97023 1.69000000
97030 1.69000000
97037 1.69000000
97172 1.69000000
97173 1.69000000