Time comparison?

Configuration
1

Is it possible to compare time ?

I have MQTT time update:

- platform: mqtt
  state_topic: "owsensors"
  name: "mqtt_owsensors_update"
  value_template: '{{ now().strftime("%X") }}'

and I want to configure automation, to set all to STATE_UNKNOWN after expiry time, something like this:

automation:

  • alias: mqtt_expire
    trigger:
    platform: template
    value_template: “{% if is_state(‘sensor.mqtt_owsensors_update’ < now().strftime(”%X") - 30) %}true{% endif %}"
    condition: state
    entity_id: sensor.mqtt_temperature
    state: STATE_UNKNOWN

How to set STATE_UNKNOWN for all sensors in one group ?