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 (
    1893, 1857, 2147, 1790, 1877, 1858, 1876, 
    1841, 1796, 2329, 2330, 1860, 2148, 
    2152, 1868, 1881, 1888, 2303, 2016, 
    2319, 1999, 2019, 2321, 2322, 2018, 
    1928, 2017, 1998, 2020, 2071, 2320, 
    2333, 2080, 2325, 2113, 2324, 2327, 
    2326, 2347, 2323, 2135, 2300, 2206, 
    2193, 2079, 2078, 1921, 2296, 2012, 
    2013, 2280, 2335, 2380, 2035, 1941, 
    2052, 2055, 1960, 1926, 1990, 2341, 
    2053, 1937, 2353, 2072, 2074, 2073, 
    2312, 2313, 2084, 2292, 2304, 1821, 
    2164, 1786, 1805, 1822, 2170, 2189, 
    2188
  ) 
  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 0.00068

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "57.36"
    },
    "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": 83,
        "rows_produced_per_join": 16,
        "filtered": "19.97",
        "index_condition": "(`cscartdevel`.`cscart_product_prices`.`product_id` in (1893,1857,2147,1790,1877,1858,1876,1841,1796,2329,2330,1860,2148,2152,1868,1881,1888,2303,2016,2319,1999,2019,2321,2322,2018,1928,2017,1998,2020,2071,2320,2333,2080,2325,2113,2324,2327,2326,2347,2323,2135,2300,2206,2193,2079,2078,1921,2296,2012,2013,2280,2335,2380,2035,1941,2052,2055,1960,1926,1990,2341,2053,1937,2353,2072,2074,2073,2312,2313,2084,2292,2304,1821,2164,1786,1805,1822,2170,2189,2188))",
        "cost_info": {
          "read_cost": "55.70",
          "eval_cost": "1.66",
          "prefix_cost": "57.36",
          "data_read_per_join": "397"
        },
        "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)))"
      }
    }
  }
}