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 (
    2305, 48558, 40449, 34674, 34668, 3862, 
    2857, 48235, 6368, 3519, 15322, 6274, 
    48559, 30368, 40381, 47828, 46583, 
    48557, 1945, 44946, 22263, 34667, 1267, 
    3863, 2859, 1105, 35730, 1107, 35177, 
    48069, 854, 44943
  ) 
  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 0.01052

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 (2305,48558,40449,34674,34668,3862,2857,48235,6368,3519,15322,6274,48559,30368,40381,47828,46583,48557,1945,44946,22263,34667,1267,3863,2859,1105,35730,1107,35177,48069,854,44943)",
          "attached_condition": "cscart_product_prices.lower_limit = 1 and cscart_product_prices.usergroup_id in (0,1)"
        }
      }
    ]
  }
}