SELECT 
  * 
FROM 
  cscart_product_feature_variants 
WHERE 
  variant_id IN (
    2526, 1882, 1855, 2470, 75, 1605, 1580, 
    1581, 58, 147, 148, 611, 126, 1604, 59, 
    837, 48, 905, 612, 87, 1577, 1582, 422, 
    64, 1578, 1579, 49, 85, 88, 50, 657, 1799, 
    2982, 431, 1856, 1870, 0, 2992, 42, 895, 
    1, 356, 43, 195, 44, 341, 121, 65
  )

Query time 0.00060

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_product_feature_variants",
          "access_type": "range",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["variant_id"],
          "rows": 48,
          "filtered": 100,
          "index_condition": "cscart_product_feature_variants.variant_id in (2526,1882,1855,2470,75,1605,1580,1581,58,147,148,611,126,1604,59,837,48,905,612,87,1577,1582,422,64,1578,1579,49,85,88,50,657,1799,2982,431,1856,1870,0,2992,42,895,1,356,43,195,44,341,121,65)"
        }
      }
    ]
  }
}