The authentication is done using JWT.
You can create a JWT token following the instruction at: https://jwt.io.
In particular, the required fields for the JSON payload for the token creation are:
iat- issued at, in epoch time.
exp- expirated at, in epoch time.
nbf- valid not before, in epoch time.
More info about the header prefix and the secret key are available in the Configuration section.
To convert the human readable datetime you can use https://www.epochconverter.com.