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 (
    444839, 428245, 418635, 426766, 438143, 
    427476, 438277, 423983, 418826, 451985, 
    420812, 455665, 404060, 455720, 420563, 
    416787, 428711, 460118, 458461, 403343, 
    405043, 402986, 417129, 414508, 403905, 
    410883, 408899, 408775, 440269, 435840, 
    444141, 410125, 453374, 429849, 427100, 
    430100, 427619, 444547, 432847, 403496, 
    431636, 455406, 435103, 415659, 443503, 
    401160, 406539, 408349
  ) 
  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 0.00234

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.198563002,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_product_prices",
          "access_type": "range",
          "possible_keys": [
            "usergroup",
            "product_id",
            "lower_limit",
            "usergroup_id"
          ],
          "key": "usergroup",
          "key_length": "9",
          "used_key_parts": ["product_id", "usergroup_id", "lower_limit"],
          "loops": 1,
          "rows": 96,
          "cost": 0.16771496,
          "filtered": 50,
          "attached_condition": "cscart_product_prices.lower_limit = 1 and cscart_product_prices.product_id in (444839,428245,418635,426766,438143,427476,438277,423983,418826,451985,420812,455665,404060,455720,420563,416787,428711,460118,458461,403343,405043,402986,417129,414508,403905,410883,408899,408775,440269,435840,444141,410125,453374,429849,427100,430100,427619,444547,432847,403496,431636,455406,435103,415659,443503,401160,406539,408349) and cscart_product_prices.usergroup_id in (0,1)"
        }
      }
    ]
  }
}