SSH トンネリング経由で Python をリモート MySQL サーバーに安全に接続するにはどうすればよいですか?

import pymysql
import paramiko
import pandas as pd
from paramiko import SSHClient
from sshtunnel import SSHTunnelForwarder
from os.path import expanduser

home = expanduser('~')
mypkey = paramiko.RSAKey.from_private_key_file(home + pkeyfilepath)

sql_hostname = 'sql_hostname'
sql_username = 'sql_username'
sql_password = 'sql_password'
sql_main_database = 'db_name'
sql_port = 3306
ssh_host = 'ssh_hostname'
ssh_user = 'ssh_username'
ssh_port = 22
sql_ip = '1.1.1.1.1'

with SSHTunnelForwarder(
        (ssh_host, ssh_port),
        ssh_username=ssh_user,
        ssh_pkey=mypkey,
        remote_bind_address=(sql_hostname, sql_port)) as tunnel:
    conn = pymysql.connect(host='127.0.0.1', user=sql_username,
            passwd=sql_password, db=sql_main_database,
            port=tunnel.local_bind_port)
    query = '''SELECT VERSION();'''
    data = pd.read_sql_query(query, conn)
    conn.close()