NewNotification.php

<?php

namespace App\Notifications;

use Illuminate\Bus\Queueable;
use Illuminate\Notifications\Notification;
use Illuminate\Contracts\Queue\ShouldQueue;
use Illuminate\Notifications\Messages\MailMessage;

class NewNotification extends Notification
{
    use Queueable;
    /**
     * @var string
     */
    protected $token;

    /**
     * Create a new notification instance.
     *
     * @param string $token
     */
    public function __construct(string $token)
    {
        $this->token = $token;
    }

    /**
     * Get the notification's delivery channels.
     *
     * @param  mixed  $notifiable
     * @return array
     */
    public function via($notifiable)
    {
        return ['mail'];
    }

    /**
     * Get the mail representation of the notification.
     *
     * @param  mixed  $notifiable
     * @return \Illuminate\Notifications\Messages\MailMessage
     */
    public function toMail($notifiable)
    {
        return (new MailMessage)
                    ->line('The introduction to the notification.')
                    ->action('Notification Action', url('/' . $this->token))
                    ->line('Thank you for using our application!');
    }

    /**
     * Get the array representation of the notification.
     *
     * @param  mixed  $notifiable
     * @return array
     */
    public function toArray($notifiable)
    {
        return [
            //
        ];
    }
}

routes.php

<?php
Route::get('notify', function () {
    $user = \App\User::find(2);
    $token = md5(microtime());
    $user->notify(new \App\Notifications\NewNotification($token));
});