src/Token.php
protected function setExpires()
    {
        $created = $this->created;

        if ($this->lifetime === null) {
            $this->lifetime = self::DEFAULT_LIFETIME;
        }

        $this->expires = $created->modify($this->lifetime);
    }
protected function setExpires()
    {
        $created = $this->created;

        if ($this->lifetime === null) {
            $this->lifetime = self::DEFAULT_LIFETIME;
        }

        $this->expires = $created->modify($this->lifetime);
    }
Set the 'expires' property by adding lifetime to the 'created'  property.

@return void