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 (
    170, 162, 168, 61, 166, 736, 734, 732, 
    733, 735, 737, 1569, 258, 257, 1783, 
    1779, 1782, 1781, 1676, 1229, 1181, 
    362, 256, 452, 420, 374, 800, 1136, 224, 
    795, 1839, 797, 798, 1409, 367, 1393, 
    484, 445, 157, 388, 585, 241, 629, 590, 
    860, 1790, 230, 413
  ) 
  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 0.00184

JSON explain

{
  "query_block": {
    "select_id": 1,
    "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": 48,
      "filtered": 9.795915604,
      "index_condition": "cscart_product_prices.product_id in (170,162,168,61,166,736,734,732,733,735,737,1569,258,257,1783,1779,1782,1781,1676,1229,1181,362,256,452,420,374,800,1136,224,795,1839,797,798,1409,367,1393,484,445,157,388,585,241,629,590,860,1790,230,413)",
      "attached_condition": "cscart_product_prices.lower_limit = 1 and cscart_product_prices.usergroup_id in (0,1)"
    }
  }
}

Result

product_id price
61 25000.00000000
157 46000.00000000
162 18000.00000000
166 18000.00000000
168 18000.00000000
170 0.00000000
224 22000.00000000
230 27000.00000000
241 0.00000000
256 42000.00000000
257 70000.00000000
258 48000.00000000
362 52000.00000000
367 43000.00000000
374 37000.00000000
388 24000.00000000
413 23500.00000000
420 42000.00000000
445 32000.00000000
452 98000.00000000
484 24000.00000000
585 26000.00000000
590 22000.00000000
629 46000.00000000
732 42000.00000000
733 32000.00000000
734 40000.00000000
735 40000.00000000
736 42000.00000000
737 32000.00000000
795 22000.00000000
797 11000.00000000
798 22000.00000000
800 23500.00000000
860 42000.00000000
1136 23500.00000000
1181 34000.00000000
1229 50000.00000000
1393 38000.00000000
1409 46000.00000000
1569 68500.00000000
1676 65000.00000000
1779 82000.00000000
1781 82000.00000000
1782 82000.00000000
1783 88000.00000000
1790 32000.00000000
1839 22000.00000000