Easy way to mute AirPods mic while on a call

Got my AirPods a couple weeks ago and I love them! A huge bonus is that the mic works very well on a call. It tunes out background noise and focuses on my voice much better than my LG Bluetooth headset.

One gripe I have is that without a mute button on the AirPods, it is cumbersome to unmute via my iPhone. My iPhone locks after a minute while talking through Bluetooth. It doesn't do this using the speakerphone. When I need to unmute, I must first unlock my iPhone. Then the phone does not instantly return to the call screen, but instead the last app I was using prior to the call. If it's an app (like my work email app that also locks) it requires another fingerprint or passcode unlock before I can easily switch back to the call. Finally, I can unmute. This can take a good 15 seconds of fumbling around.

Am I missing something? There's got to be an easier way to mute/unmute my iPhone while on a Bluetooth device that doesn't have a built in mute function..?

Thanks!