SELECT 
  a.code, 
  b.state 
FROM 
  cscart_states as a 
  LEFT JOIN cscart_state_descriptions as b ON b.state_id = a.state_id 
  AND b.lang_code = 'ru' 
WHERE 
  a.country_code = 'RU' 
ORDER BY 
  b.state

Query time 0.00009

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "207.00"
    },
    "ordering_operation": {
      "using_temporary_table": true,
      "using_filesort": true,
      "cost_info": {
        "sort_cost": "80.00"
      },
      "nested_loop": [
        {
          "table": {
            "table_name": "a",
            "access_type": "ref",
            "possible_keys": [
              "cs",
              "country_code"
            ],
            "key": "cs",
            "used_key_parts": [
              "country_code"
            ],
            "key_length": "8",
            "ref": [
              "const"
            ],
            "rows_examined_per_scan": 80,
            "rows_produced_per_join": 80,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "15.00",
              "eval_cost": "16.00",
              "prefix_cost": "31.00",
              "data_read_per_join": "8K"
            },
            "used_columns": [
              "state_id",
              "country_code",
              "code"
            ]
          }
        },
        {
          "table": {
            "table_name": "b",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "state_id",
              "lang_code"
            ],
            "key_length": "9",
            "ref": [
              "44mm_ru.a.state_id",
              "const"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 80,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "80.00",
              "eval_cost": "16.00",
              "prefix_cost": "127.00",
              "data_read_per_join": "61K"
            },
            "used_columns": [
              "state_id",
              "lang_code",
              "state"
            ]
          }
        }
      ]
    }
  }
}