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 (
    1900, 1813, 1767, 1764, 1893, 1857, 2147, 
    1790, 1877, 1858, 1876, 1841, 1796, 
    2329, 2330, 1860, 2148, 2152, 1868, 
    1881, 2028, 2118, 2116, 2117, 1966, 
    1967, 1965, 2026, 2027, 2131, 1938, 
    2025, 1899, 1910, 1872, 1850, 1883, 
    1810, 1851, 1884, 1907, 1909, 1908, 
    2155, 1862, 2161, 1978, 1902, 1979, 
    2162, 1890, 1901, 1854, 1833, 1844, 
    1804, 1756, 1834, 1788, 1809, 1778, 
    1865, 2160, 1866
  ) 
  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 0.00055

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "46.16"
    },
    "grouping_operation": {
      "using_filesort": false,
      "table": {
        "table_name": "cscart_product_prices",
        "access_type": "range",
        "possible_keys": [
          "usergroup",
          "product_id",
          "lower_limit",
          "usergroup_id"
        ],
        "key": "product_id",
        "used_key_parts": [
          "product_id"
        ],
        "key_length": "3",
        "rows_examined_per_scan": 67,
        "rows_produced_per_join": 13,
        "filtered": "19.97",
        "index_condition": "(`cscartdevel`.`cscart_product_prices`.`product_id` in (1900,1813,1767,1764,1893,1857,2147,1790,1877,1858,1876,1841,1796,2329,2330,1860,2148,2152,1868,1881,2028,2118,2116,2117,1966,1967,1965,2026,2027,2131,1938,2025,1899,1910,1872,1850,1883,1810,1851,1884,1907,1909,1908,2155,1862,2161,1978,1902,1979,2162,1890,1901,1854,1833,1844,1804,1756,1834,1788,1809,1778,1865,2160,1866))",
        "cost_info": {
          "read_cost": "44.82",
          "eval_cost": "1.34",
          "prefix_cost": "46.16",
          "data_read_per_join": "321"
        },
        "used_columns": [
          "product_id",
          "price",
          "percentage_discount",
          "lower_limit",
          "usergroup_id"
        ],
        "attached_condition": "((`cscartdevel`.`cscart_product_prices`.`lower_limit` = 1) and (`cscartdevel`.`cscart_product_prices`.`usergroup_id` in (0,1)))"
      }
    }
  }
}