No the MX does not have a metronome. It has a Rhythm Pattern feature and is iOS compatible - you can connect an iPhone/iPad and use an app.

From the Owner’s Manual
“This instrument features a wealth of dynamic Rhythm Patterns in wide variety of musical genres. You can play the keyboard along with Rhythm Pattern playback—a truly inspiring way to perform! The instrument also conveniently lets you play back MIDI and Audio data contained in USB flash memory—letting you easily use Song data created on computer during live performance, without needing a computer! Plus, an [AUX IN] jack allows you to connect a portable music player, so that you can play the keyboard along with your favorite songs.”

See page 21 on Playing back Rhythm Patterns