Laravel Registration Key with Validation - php

Question

I'm currently trying to modify the base Laravel Authentication to include the use of a key created in the database, I've included another field named "key" which I've been able to get the registration to check via a model, the issue is that if the key is incorrectly input I haven't been able to let the user know the key is incorrect.
Current RegistrationController.php
protected function validator(array $data)
{
return Validator::make($data, [
'name' => ['required', 'string', 'max:255'],
'email' => ['required', 'string', 'email', 'max:255', 'unique:users'],
'password' => ['required', 'string', 'min:8', 'confirmed'],
'key' => ['required'],
]);
}
/**
* Handle a registration request for the application.
*
* #param \Illuminate\Http\Request $request
* #return \Illuminate\Http\Response
*/
public function register(Request $request)
{
$d = Key::where('key', $request->only(['key'])['key'])->first();
if($d != null){
$this->validator($request->all())->validate();
event(new Registered($user = $this->create($request->all())));
$this->guard()->login($user);
if ($response = $this->registered($request, $user)) {
return $response;
}
return $request->wantsJson()
? new Response('', 201)
: redirect($this->redirectPath());
}
else{
$this->validator($request->all())->validate();
return view('auth.register')->withErrors(['key', 'This key was not found']);
}
}
I've tried to modify the validate method to include same but when testing using same:12345 it looks for a variable called 12345 instead of checking if the key is the same as 12345, how do I change the validation to do what I've done in the register method to check the models instead.