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 (
    1987, 2110, 2111, 2112, 1900, 1813, 1820, 
    2366, 1897, 1750, 1924, 2227, 2204, 
    2010, 2309, 2060, 2122, 2274, 2061, 
    1918, 1913, 1958, 2290, 1751, 1957, 
    2202, 1814, 2331, 1748, 2005, 2214, 
    2342, 2215, 2211, 2225, 2212, 2213, 
    2226, 2151, 1882, 1815, 1853, 1759, 
    2001, 2276, 2231, 2281, 2379, 2388, 
    2115, 1929, 2373, 2372, 2374, 1760, 
    1807, 1847, 2363, 1816, 2146, 2201, 
    2386, 2359, 2279, 1843, 1859, 1794, 
    1793, 1817, 1795, 2278, 1818, 1784, 
    1819, 1849, 2338, 2383, 2337, 2336, 
    2389
  ) 
  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 0.00071

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": "19.99",
        "index_condition": "(`cscartdevel`.`cscart_product_prices`.`product_id` in (1987,2110,2111,2112,1900,1813,1820,2366,1897,1750,1924,2227,2204,2010,2309,2060,2122,2274,2061,1918,1913,1958,2290,1751,1957,2202,1814,2331,1748,2005,2214,2342,2215,2211,2225,2212,2213,2226,2151,1882,1815,1853,1759,2001,2276,2231,2281,2379,2388,2115,1929,2373,2372,2374,1760,1807,1847,2363,1816,2146,2201,2386,2359,2279,1843,1859,1794,1793,1817,1795,2278,1818,1784,1819,1849,2338,2383,2337,2336,2389))",
        "cost_info": {
          "read_cost": "57.85",
          "eval_cost": "1.76",
          "prefix_cost": "59.61",
          "data_read_per_join": "422"
        },
        "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)))"
      }
    }
  }
}