SELECT 
  * 
FROM 
  cscart_product_feature_variants 
WHERE 
  variant_id IN (
    3719, 3709, 4862, 1913, 4867, 1858, 1882, 
    1855, 2178, 2547, 1880, 1910, 2128, 
    1288, 176, 1856, 1983, 1859, 1870, 360, 
    1293, 1349, 1290, 1447, 1376, 860, 491, 
    1338, 1291, 1410, 1402, 0
  )

Query time 0.00058

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": 32,
          "filtered": 100,
          "index_condition": "cscart_product_feature_variants.variant_id in (3719,3709,4862,1913,4867,1858,1882,1855,2178,2547,1880,1910,2128,1288,176,1856,1983,1859,1870,360,1293,1349,1290,1447,1376,860,491,1338,1291,1410,1402,0)"
        }
      }
    ]
  }
}