SELECT 
  f.*, 
  d.description 
FROM 
  ushop_custom_fields_options as f 
  LEFT JOIN ushop_custom_fields_descriptions as d ON d.object_id = f.element_id 
  AND d.lang_code = 'es' 
WHERE 
  1 
  AND f.status = 'A' 
ORDER BY 
  f.position

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "2.15"
    },
    "ordering_operation": {
      "using_filesort": true,
      "cost_info": {
        "sort_cost": "1.00"
      },
      "nested_loop": [
        {
          "table": {
            "table_name": "f",
            "access_type": "ALL",
            "rows_examined_per_scan": 3,
            "rows_produced_per_join": 1,
            "filtered": "33.33",
            "cost_info": {
              "read_cost": "0.70",
              "eval_cost": "0.10",
              "prefix_cost": "0.80",
              "data_read_per_join": "792"
            },
            "used_columns": [
              "element_id",
              "parent_id",
              "element_type",
              "value",
              "position",
              "required",
              "status"
            ],
            "attached_condition": "(`marketplace`.`f`.`status` = 'A')"
          }
        },
        {
          "table": {
            "table_name": "d",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "object_id",
              "lang_code"
            ],
            "key_length": "11",
            "ref": [
              "marketplace.f.element_id",
              "const"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 1,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "0.25",
              "eval_cost": "0.10",
              "prefix_cost": "1.15",
              "data_read_per_join": "24"
            },
            "used_columns": [
              "object_id",
              "description",
              "lang_code"
            ]
          }
        }
      ]
    }
  }
}