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 (
    1893, 38074, 49164, 48846, 1103, 1102, 
    1104, 1105, 1107, 43825, 1106, 2620, 
    40452, 3471, 39613, 40454, 40453, 1781, 
    48843, 1755, 40455, 48844, 1784, 5765, 
    48850, 1756, 6543, 5759, 1745, 23481, 
    48847, 5770
  ) 
  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 0.00260

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 (1893,38074,49164,48846,1103,1102,1104,1105,1107,43825,1106,2620,40452,3471,39613,40454,40453,1781,48843,1755,40455,48844,1784,5765,48850,1756,6543,5759,1745,23481,48847,5770)",
          "attached_condition": "cscart_product_prices.lower_limit = 1 and cscart_product_prices.usergroup_id in (0,1)"
        }
      }
    ]
  }
}