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 (
    5642, 5643, 5644, 5645, 5646, 5647, 5648, 
    5649, 5650, 5651, 5652, 5653, 5654, 
    5655, 5656, 5657, 5658, 5659, 5660, 
    5661, 5662, 5663, 5664, 5665, 5666, 
    5667, 3137, 1473, 1474, 1475, 1476, 
    1477, 5182, 5183, 5184, 5185, 5186, 
    5187, 1461, 1462, 1463, 1464, 1465, 
    5170, 5171, 5172, 5173, 5174, 5175, 
    1878, 1879, 1880, 1881, 1882, 1883, 
    1884, 1885, 1886, 1887, 1888, 1889, 
    1890, 1891, 1892, 1893, 1894, 1895, 
    1896, 1897, 1898, 1899, 1900, 1901, 
    1902, 1903, 1904, 1905, 1906, 1907, 
    1908, 1909, 1910, 1911, 1912, 1913, 
    1914, 1915, 1916, 1917, 1918, 1919, 
    1920, 1921, 1922, 1923, 1924
  ) 
  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 0.00162

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "67.66"
    },
    "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": 97,
        "rows_produced_per_join": 19,
        "filtered": "20.00",
        "index_condition": "(`gaseus`.`cscart_product_prices`.`product_id` in (5642,5643,5644,5645,5646,5647,5648,5649,5650,5651,5652,5653,5654,5655,5656,5657,5658,5659,5660,5661,5662,5663,5664,5665,5666,5667,3137,1473,1474,1475,1476,1477,5182,5183,5184,5185,5186,5187,1461,1462,1463,1464,1465,5170,5171,5172,5173,5174,5175,1878,1879,1880,1881,1882,1883,1884,1885,1886,1887,1888,1889,1890,1891,1892,1893,1894,1895,1896,1897,1898,1899,1900,1901,1902,1903,1904,1905,1906,1907,1908,1909,1910,1911,1912,1913,1914,1915,1916,1917,1918,1919,1920,1921,1922,1923,1924))",
        "cost_info": {
          "read_cost": "65.72",
          "eval_cost": "1.94",
          "prefix_cost": "67.66",
          "data_read_per_join": "465"
        },
        "used_columns": [
          "product_id",
          "price",
          "percentage_discount",
          "lower_limit",
          "usergroup_id"
        ],
        "attached_condition": "((`gaseus`.`cscart_product_prices`.`lower_limit` = 1) and (`gaseus`.`cscart_product_prices`.`usergroup_id` in (0,1)))"
      }
    }
  }
}