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 (
    1928, 1929, 1911, 1925, 1926, 1901, 1908, 
    1923, 1922, 1921, 1909, 1920, 1919, 
    1918, 1917, 1916, 1915, 1914, 1883, 
    1913, 1912, 1910, 1903, 1902, 1905, 
    1904, 1872, 1899, 1898, 1897, 1896, 
    1873, 1895, 1894, 1893, 1891, 1659, 
    1890, 1889, 1888, 1887, 1871, 1885, 
    1886, 1884, 1869, 1882, 1881
  ) 
  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 0.00179

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_product_prices",
      "access_type": "range",
      "possible_keys": ["usergroup", "product_id", "lower_limit", "usergroup_id"],
      "key": "product_id",
      "key_length": "3",
      "used_key_parts": ["product_id"],
      "rows": 60,
      "filtered": 9.795915604,
      "index_condition": "cscart_product_prices.product_id in (1928,1929,1911,1925,1926,1901,1908,1923,1922,1921,1909,1920,1919,1918,1917,1916,1915,1914,1883,1913,1912,1910,1903,1902,1905,1904,1872,1899,1898,1897,1896,1873,1895,1894,1893,1891,1659,1890,1889,1888,1887,1871,1885,1886,1884,1869,1882,1881)",
      "attached_condition": "cscart_product_prices.lower_limit = 1 and cscart_product_prices.usergroup_id in (0,1)"
    }
  }
}

Result

product_id price
1659 465000.00000000
1869 28000.00000000
1871 48000.00000000
1872 0.00000000
1873 63000.00000000
1881 44000.00000000
1882 48000.00000000
1883 30000.00000000
1884 48000.00000000
1885 260000.00000000
1886 48000.00000000
1887 48000.00000000
1888 48000.00000000
1889 48000.00000000
1890 48000.00000000
1891 97000.00000000
1893 158000.00000000
1894 158000.00000000
1895 158000.00000000
1896 63000.00000000
1897 63000.00000000
1898 0.00000000
1899 0.00000000
1901 38000.00000000
1902 148000.00000000
1903 42000.00000000
1904 26000.00000000
1905 82000.00000000
1908 23500.00000000
1909 60000.00000000
1910 32000.00000000
1911 52000.00000000
1912 60000.00000000
1913 60000.00000000
1914 55000.00000000
1915 72000.00000000
1916 28000.00000000
1917 32000.00000000
1918 13000.00000000
1919 23500.00000000
1920 23500.00000000
1921 60000.00000000
1922 22500.00000000
1923 46000.00000000
1925 28000.00000000
1926 23000.00000000
1928 23000.00000000
1929 28000.00000000