HA - Input_boolean activate timer sensor

#----------------------------------------------------------
# Local Date and time
#----------------------------------------------------------
sensor:
  - platform: time_date
    display_options:
      - 'time'
    scan_interval: 55   #Update once every 55 second

  #----------------------------------------------------------
  # Washer 'on' timer sensor
  #----------------------------------------------------------
  - platform: template
    sensors:
      vaskemaskine_entity_on_time:
        value_template: >-
          {% if is_state("input_boolean.vaskemaskine_rengoering", "on") -%}
          {{ (as_timestamp(now())- as_timestamp(states.input_boolean.vaskemaskine_rengoering.last_changed)) | timestamp_custom('%H:%M:%S', false) }}
          {%- else -%}
          0
          {%- endif %}
        entity_id: sensor.time