//  check if expired
    Carbon::parse($createdAt)->addSeconds($this->expires)->isPast();


    // diff in seconds
    $then = Carbon::now()->addMinute();
    $now = Carbon::now();
    
    $then->diffInSeconds($now, false) // -60
    $now->diffInSeconds($then, false) // 60

    // parse string
    let will_end = '2019-02-01 10:00:00';
    let then = moment(new Date(will_end)); 
    
    // diff in seconds
    let then = moment().add(1, 'minute'); 
    let now = moment();
    
    then.diff(now, 'seconds'); // 60
    now.diff(then, 'seconds'); // -60