Check if event was scheduled – schedule event only once

Have you ever heard of Rubber Ducking?

The official documentation has an answer:

if ( ! wp_next_scheduled( 'woofio_hourly' ) ) {
    wp_schedule_event( time(), 'hourly', 'woofio_hourly' );
}

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)