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 (
    1914, 1915, 1761, 2203, 1789, 1811, 1791, 
    1889, 1836, 1799, 1845, 1792, 1905, 
    1806, 1837, 2282, 2002, 1940, 2295, 
    2283, 1970, 2387, 2014, 2355, 1996, 
    2286, 2285, 2310, 1997, 1956, 1971, 
    2316, 1955, 2334, 2108, 2360, 2287, 
    2288, 2009, 1950, 2109, 2107, 2221, 
    2023, 2123, 1982, 1944, 2031, 2032, 
    1920, 2033, 2034, 2165, 2223, 2190, 
    1758, 2365, 2067, 2294, 2070, 2069, 
    1835, 1871, 2241, 2351, 2091, 1959, 
    1981, 2137, 2340, 1745, 2209, 2063, 
    2370, 2377, 1916, 2381, 2392, 1838, 
    1766
  ) 
  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 0.00075

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "59.61"
    },
    "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": 88,
        "rows_produced_per_join": 17,
        "filtered": "19.97",
        "index_condition": "(`cscartdevel`.`cscart_product_prices`.`product_id` in (1914,1915,1761,2203,1789,1811,1791,1889,1836,1799,1845,1792,1905,1806,1837,2282,2002,1940,2295,2283,1970,2387,2014,2355,1996,2286,2285,2310,1997,1956,1971,2316,1955,2334,2108,2360,2287,2288,2009,1950,2109,2107,2221,2023,2123,1982,1944,2031,2032,1920,2033,2034,2165,2223,2190,1758,2365,2067,2294,2070,2069,1835,1871,2241,2351,2091,1959,1981,2137,2340,1745,2209,2063,2370,2377,1916,2381,2392,1838,1766))",
        "cost_info": {
          "read_cost": "57.85",
          "eval_cost": "1.76",
          "prefix_cost": "59.61",
          "data_read_per_join": "421"
        },
        "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)))"
      }
    }
  }
}