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 (
    67356, 67355, 67354, 67353, 67352, 67351, 
    67350, 67349, 67348, 67347, 67346, 
    67345, 67344, 67314, 67313, 76804, 
    76803, 76802, 76801, 76800, 76799, 
    76798, 76797, 76796, 76795, 76794, 
    67193, 67179, 67178, 67177, 67176, 
    67175, 67174, 67173, 67172, 67171, 
    67170, 67169, 67168, 67167
  ) 
  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 0.00065

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