uniqueToken.php

<?php

$user = User::first($id)

//Generate Token
do {
    $token = str_random(128);
} while (User::where('token', $token)->exists());

$user->token = $token;
$user->save();


//Check Token
if(User::where('token', $token)->exists()){
    $user = User::where('token', $token)->first();
    //Do Something
}