SELECT 
  cscart_ult_product_prices.product_id, 
  MIN(
    IF(
      cscart_ult_product_prices.percentage_discount = 0, 
      cscart_ult_product_prices.price, 
      cscart_ult_product_prices.price - (
        cscart_ult_product_prices.price * cscart_ult_product_prices.percentage_discount
      )/ 100
    )
  ) AS price 
FROM 
  cscart_ult_product_prices 
WHERE 
  cscart_ult_product_prices.product_id IN (
    74051, 74050, 74049, 74048, 74047, 74046, 
    74045, 74044, 74043, 73817, 73816, 
    74713, 74712, 74711, 74710, 74709, 
    74708, 74707, 74706, 74705, 74704, 
    74703, 74702, 74701, 74700, 74699, 
    74698, 74697, 74696, 74695, 74694, 
    74466, 74601, 74540, 74092, 73927, 
    73907, 73906, 73824, 73952
  ) 
  AND cscart_ult_product_prices.lower_limit = 1 
  AND cscart_ult_product_prices.company_id = 1 
  AND cscart_ult_product_prices.usergroup_id IN (0, 0, 1) 
GROUP BY 
  cscart_ult_product_prices.product_id

Query time 0.00068

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE cscart_ult_product_prices range usergroup,product_id,company_id,lower_limit,usergroup_id usergroup 13 1 Using where