Route [login] not defined.Route [login] not defined.

To check either request includes token or not make your own middleware.

php artisan make:middleware CheckApiToken

public function handle($request, Closure $next)
{
    if(!empty(trim($request->input('api_token')))){

        $is_exists = User::where('id' , Auth::guard('api')->id())->exists();
        if($is_exists){
            return $next($request);
        }
    }
        return response()->json('Invalid Token', 401);
}You're trying to redirect to a named route whose name is login, but you have
no routes with that name:

Route::post('login', [ 'as' => 'login', 'uses' => 'LoginController@do']);

The 'as' portion of the second parameter defines the name of the route. The 
first string parameter defines its route.Use Postman and set the Header `Accept: application/json` otherwise Laravel
Passport would never know it's an API client and thus redirect to a /login 
page for the web.