all kinds of inquiries about all kinds of installations, there are a lot of bad ones, but they still report an error

system: centos7
Framework: tornado
error message

Traceback (most recent call last):
  File "/home/king/PycharmProjects/untitled4/server.py", line 5, in <module>
    import torndb
  File "/home/king/PycharmProjects/untitled/untitled4/lib/python3.5/site-packages/torndb.py", line 33, in <module>
    import MySQLdb.constants
ImportError: No module named "MySQLdb"

Program Code

-sharp coding:utf-8

import tornado.web
import tornado.ioloop
import torndb

class IndexHandler(tornado.web.RequestHandler):
    """"""
    def get(self):
        """httpget"""

        self.db = torndb.Connection(
            host="127.0.0.1",
            database="itcast",
            user="root",
            password="root"
        )
        self.db.execute("create database test1 ")
        self.write("Hello Itcast!")

if __name__ == "__main__":
    app = tornado.web.Application([
        (r"/", IndexHandler),
    ])
    app.listen(8000)
    tornado.ioloop.IOLoop.current().start()

torndb has been installed

(untitled4) [king@localhost untitled4]$ pip3 install torndb
Requirement already satisfied: torndb in /home/king/PycharmProjects/untitled/untitled4/lib/python3.5/site-packages

MySQL-python has been installed

(untitled4) [king@localhost untitled4]$ sudo yum install MySQL-python
[sudo] password for king: 
:fastestmirror, langpacks
Loading mirror speeds from cached hostfile
 * base: centos.ustc.edu.cn
 * epel: ftp.yz.yamagata-u.ac.jp
 * extras: centos.ustc.edu.cn
 * updates: centos.ustc.edu.cn
 MySQL-python-1.2.5-1.el7.x86_64