private function setExpiration($expires_in)
    {
        $this->expiresAtTimestamp = time() + $expires_in;
        $this->expiresAt = date('Y-m-d H:i:s', time() + $expires_in);
    }
private function setExpiration($expires_in)
    {
        $this->expiresAtTimestamp = time() + $expires_in;
        $this->expiresAt = date('Y-m-d H:i:s', time() + $expires_in);
    }
private function setExpiration ( $ expires_in ) { $ this -> expiresAtTimestamp = time ( ) + $ expires_in ; $ this -> expiresAt = date ( 'Y-m-d H:i:s' , time ( ) + $ expires_in ) ; }
Set the expiration time for the token
@param $expires_in
Set the expiration time for the token