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 (
    5992, 1535, 41429, 1765, 47600, 47184, 
    45508, 34675, 6093, 31912, 5782, 47012, 
    3580, 6354, 34670, 31965, 37098, 26892, 
    48998, 1717, 40450, 6364, 37092, 41291, 
    2154, 4513, 5785, 737, 6611, 26880, 
    35740, 41279
  ) 
  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 0.00196

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_product_prices",
          "access_type": "range",
          "possible_keys": [
            "usergroup",
            "product_id",
            "lower_limit",
            "usergroup_id"
          ],
          "key": "product_id",
          "key_length": "3",
          "used_key_parts": ["product_id"],
          "rows": 32,
          "filtered": 99.9960556,
          "index_condition": "cscart_product_prices.product_id in (5992,1535,41429,1765,47600,47184,45508,34675,6093,31912,5782,47012,3580,6354,34670,31965,37098,26892,48998,1717,40450,6364,37092,41291,2154,4513,5785,737,6611,26880,35740,41279)",
          "attached_condition": "cscart_product_prices.lower_limit = 1 and cscart_product_prices.usergroup_id in (0,1)"
        }
      }
    ]
  }
}