Lumen Eloquent save() don't update data at database - php

Question

I have buyer model, but when i want to change current it's data and save it, it won't save. $buyer->save() return 1 but data at my database won't change.
P.S.
My database has id, created_at and updated_at fields. And $buyer is not empty, it's object with data that i request ('pCode', 'banned', 'hwid')
My code
namespace App\Http\Controllers;
use App\TGOBuyer as Buyer;
class SubController extends Controller
{
public function ban($key){
$buyer = Buyer::where('pCode', $key)->select('pCode', 'banned', 'hwid')->first();
if (!$buyer || $buyer->banned)
return response()->json(['wrong' => 'key']);
$buyer->comment = 'test';
$buyer->banned = 1;
$buyer->save();
}
}
Buyer model
namespace App;
use Illuminate\Database\Eloquent\Model;
class TGOBuyer extends Model {
protected $table = 'buyers';
/**
* The attributes that are mass assignable.
*
* #var array
*/
protected $fillable = [
'banned', 'comment', 'pCode', 'hwid'
];
}
Update
I tryed to return $buyer->id and it gives me null, i don't get it why it happens.
This is my db
CREATE TABLE IF NOT EXISTS `buyers` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`pCode` varchar(20) NOT NULL,
`banned` tinyint(1) NOT NULL DEFAULT '0',
`comment` text NOT NULL,
`created_at` datetime NOT NULL,
`updated_at` datetime NOT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `pCode` (`pCode`),
UNIQUE KEY `id_2` (`id`),
KEY `id` (`id`),
KEY `hwid` (`hwid`),
KEY `pID` (`pID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=22468 ;

Answer 1

I get it. I just need to include id to my select query. Now all work's fine.
$buyer = Buyer::where('pCode', $key)->select('id', 'pCode', 'banned', 'hwid')->first();