SELECT 
  cscart_product_feature_variants.variant_id, 
  cscart_product_feature_variants.position, 
  cscart_product_feature_variants.color, 
  cscart_product_feature_variant_descriptions.variant 
FROM 
  cscart_product_feature_variants 
  LEFT JOIN cscart_product_feature_variant_descriptions ON cscart_product_feature_variants.variant_id = cscart_product_feature_variant_descriptions.variant_id 
  AND cscart_product_feature_variant_descriptions.lang_code = 'en' 
WHERE 
  cscart_product_feature_variants.variant_id IN (
    135, 1251, 129, 1268, 1228, 1229, 1230, 
    1232, 1231, 1234, 1233, 1235, 1238, 
    1236, 1237, 1239, 1242, 1240, 1241, 
    1273, 1274, 1275, 1276, 1277, 1278, 
    1279, 1280, 1281, 1272
  ) 
ORDER BY 
  cscart_product_feature_variants.position ASC, 
  cscart_product_feature_variant_descriptions.variant ASC

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.08452759,
    "filesort": {
      "sort_key": "cscart_product_feature_variants.position, cscart_product_feature_variant_descriptions.variant",
      "temporary_table": {
        "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"],
              "loops": 1,
              "rows": 29,
              "cost": 0.04548163,
              "filtered": 100,
              "attached_condition": "cscart_product_feature_variants.variant_id in (135,1251,129,1268,1228,1229,1230,1232,1231,1234,1233,1235,1238,1236,1237,1239,1242,1240,1241,1273,1274,1275,1276,1277,1278,1279,1280,1281,1272)"
            }
          },
          {
            "table": {
              "table_name": "cscart_product_feature_variant_descriptions",
              "access_type": "eq_ref",
              "possible_keys": ["PRIMARY"],
              "key": "PRIMARY",
              "key_length": "9",
              "used_key_parts": ["variant_id", "lang_code"],
              "ref": [
                "u985510652_ecartify.cscart_product_feature_variants.variant_id",
                "const"
              ],
              "loops": 29,
              "rows": 1,
              "cost": 0.03904596,
              "filtered": 100,
              "attached_condition": "trigcond(cscart_product_feature_variant_descriptions.lang_code = 'en')"
            }
          }
        ]
      }
    }
  }
}