SELECT 
  a.code, 
  b.country 
FROM 
  cscart_countries as a 
  LEFT JOIN cscart_country_descriptions as b ON b.code = a.code 
  AND b.lang_code = 'pl' 
WHERE 
  a.status = 'A' 
ORDER BY 
  b.country

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "129.55"
    },
    "ordering_operation": {
      "using_temporary_table": true,
      "using_filesort": true,
      "cost_info": {
        "sort_cost": "87.00"
      },
      "nested_loop": [
        {
          "table": {
            "table_name": "a",
            "access_type": "ref",
            "possible_keys": [
              "status"
            ],
            "key": "status",
            "used_key_parts": [
              "status"
            ],
            "key_length": "3",
            "ref": [
              "const"
            ],
            "rows_examined_per_scan": 87,
            "rows_produced_per_join": 87,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "3.40",
              "eval_cost": "8.70",
              "prefix_cost": "12.10",
              "data_read_per_join": "4K"
            },
            "used_columns": [
              "code",
              "status"
            ]
          }
        },
        {
          "table": {
            "table_name": "b",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "code",
              "lang_code"
            ],
            "key_length": "12",
            "ref": [
              "cscartdevel.a.code",
              "const"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 87,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "21.75",
              "eval_cost": "8.70",
              "prefix_cost": "42.55",
              "data_read_per_join": "33K"
            },
            "used_columns": [
              "code",
              "lang_code",
              "country"
            ]
          }
        }
      ]
    }
  }
}