Absolutely:

module: "MMM-mqtt", position: "bottom_right", header: "Garage rear door", config: { mqttServer: "mqtts://username:key@io.adafruit.com:8883", topic: "username/feeds/feed-name", loadingText: "waiting for event...", interval: 60000, }

Obviously replacing username, key and feed-name.
I am having an issue currently with the mirror showing “MQTT server is offline” after a short time and mirror is not picking up any new messages published :(

Hope that helps.