MQTT publish system time

I would like to publish on MQTT server the system time when the the temperature sensor was last updated. How can I get the system time?
My code is below:
alias: Time Update
hide_entity: False
platform: mqtt
topic: “ESP8266/temperature”
service: mqtt.publish
topic: “ESP8266/data”
payload_template: ‘{{now}}’
Unfortunatly it is publishing the folowing string “<function now at 0x765cca08>”.
I was thinking is the time in Unix format, but seems to do not change from an update to another.
What is wrong?

I think that now has been changed to now(), as they are functions not variables now.

You’re right, many thanks.