JDBC-Input-Plug-In unable to execute SELECT COUTN(*) FROM sys.session

I want to use Logstash to get the current count of all sessions on my MySQL DB every second.

Thats my configuration for the pipeline:

input {
  jdbc {
    jdbc_driver_library => "/usr/share/java/mysql-connector-java-5.1.45.jar"
    jdbc_driver_class => "com.mysql.jdbc.Driver"
    jdbc_connection_string => "jdbc:mysql://localhost:3306/sys?serverTimezone=UTC"
    jdbc_user => "user"
    jdbc_password => "password"
    schedule => "* * * * *"
    statement => "SELECT COUNT(*) AS count_sessions FROM sys.session"
   }
}

output {
  elasticsearch {
    hosts => ["localhost:19200"]
    index => "mysql-session-count-live-%{+YYYY.MM.dd}"
  }
}

if I run this config I´m getting no error, but Logstash can´t execute the query and can´t be closed via systemctl stop logstash.service anymore. It says: blocked on starting worker...

Any Ideas why this happens?