FLASK: How to establish connection with mysql server?

from flask import Flask
from flaskext.mysql import MySQL

app = Flask(__name__)
mysql = MySQL()
app.config['MYSQL_DATABASE_USER'] = ''
app.config['MYSQL_DATABASE_PASSWORD'] = ''
app.config['MYSQL_DATABASE_DB'] = ''
app.config['MYSQL_DATABASE_HOST'] = ''
mysql.init_app(app)

@celery.task
def db_connect_things(): 
    conn = mysql.connect()
    cursor =conn.cursor()
    sql_query = """select from where """
    cursor.execute(sql_query)
    ...
   

from celery import Celery
celery = Celery(__name__)
celery = Celery('tasks', broker=) # rabbit,redis, ..
celery.conf.update({'CELERY_ACCEPT_CONTENT': ['pickle', 'json', 'msgpack', 'yaml']})
celery.conf.add_defaults(...)

celery.conf.update(CELERYBEAT_SCHEDULE={
    'db_connect_things': {
        'task': 'application.lib.tasks.db_connect_things',
        'schedule': crontab(minute=0, hour='*/12'),
    }})

class ContextTask(celery.Task):
...