Displaying last sensor modification time in lovelace

i am using a temperature sensor:

  - platform: mqtt
    name: 'Bed Room Temperature'
    state_topic: "home/weatherstation2/temperature"
    value_template: "{{ value_json.t }}"
    unit_of_measurement: "C"

i am displaying its value in lovelace:

  - type: horizontal-stack
    cards:
    - type: sensor
      entity: sensor.bed_room_temperature
      graph: none
      unit: c
      name: BR

i would like to show the last time that the sensor got updated near the temperature value itself - what is the best way to do this?

anyone has an idea?