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 (
    357, 354, 103, 155, 763, 15, 1223, 304, 
    1130, 337, 1135, 366, 1137, 1138, 1271, 
    1192, 1173, 142, 143, 369, 1313, 20, 
    16, 144, 145, 97, 52, 291, 76, 313, 1213, 
    1348, 1349, 801, 604
  ) 
  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 0.00145

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": 35,
      "filtered": 7.142855167,
      "index_condition": "cscart_product_prices.product_id in (357,354,103,155,763,15,1223,304,1130,337,1135,366,1137,1138,1271,1192,1173,142,143,369,1313,20,16,144,145,97,52,291,76,313,1213,1348,1349,801,604)",
      "attached_condition": "cscart_product_prices.lower_limit = 1 and cscart_product_prices.usergroup_id in (0,1)"
    }
  }
}

Result

product_id price
15 0.00000000
16 85909.00000000
20 44400.00000000
52 0.00000000
76 234000.00000000
97 85909.00000000
103 0.00000000
142 57600.00000000
143 57600.00000000
144 85909.00000000
145 85909.00000000
155 0.00000000
291 105600.00000000
304 0.00000000
313 0.00000000
337 0.00000000
354 0.00000000
357 12000.00000000
366 0.00000000
369 0.00000000
604 0.00000000
763 0.00000000
801 0.00000000
1130 0.00000000
1135 0.00000000
1137 0.00000000
1138 0.00000000
1173 30000.00000000
1192 15500.00000000
1213 21000.00000000
1223 23000.00000000
1271 1600000.00000000
1313 225000.00000000
1348 57000.00000000
1349 67000.00000000