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 (
    1896, 1894, 49873, 1057, 1716, 43824, 
    34667, 2238, 34666, 1895, 1715, 5547, 
    43823, 21780, 5548, 46737, 5556, 16607, 
    46735, 5554, 2113, 5551, 5553, 3470, 
    3469, 46739, 16601, 16612, 1754, 6529, 
    27350, 21600
  ) 
  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 0.00164

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 (1896,1894,49873,1057,1716,43824,34667,2238,34666,1895,1715,5547,43823,21780,5548,46737,5556,16607,46735,5554,2113,5551,5553,3470,3469,46739,16601,16612,1754,6529,27350,21600)",
          "attached_condition": "cscart_product_prices.lower_limit = 1 and cscart_product_prices.usergroup_id in (0,1)"
        }
      }
    ]
  }
}