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 (
    63035, 63034, 63033, 63032, 63031, 63030, 
    63029, 63028, 63027, 63026, 63025, 
    63024, 63023, 63022, 63021, 62566, 
    62565, 62564, 62563, 62562
  ) 
  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 0.00062

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
62562 1.69000000
62563 1.69000000
62564 1.69000000
62565 1.69000000
62566 8.99000000
63021 1.69000000
63022 1.69000000
63023 1.69000000
63024 1.69000000
63025 1.69000000
63026 1.69000000
63027 1.69000000
63028 1.69000000
63029 1.69000000
63030 1.69000000
63031 1.69000000
63032 1.69000000
63033 1.69000000
63034 1.69000000
63035 1.69000000