I want to make a custom middleware in laravel but i have not idea how to supply token input

If you use this middleware for API, you can pass secret key in header at every request and function handle in EnsureTokenIsValid should look like this

public function handle(Request $request, Closure $next){
        if ($request->header('secret_key') !== 'your-secret-key'){
            // logic here
        }
        return $next($request);
}

If you use it for normal http requests pass it in body or query params

public function handle(Request $request, Closure $next){
        if ($request->get('secret_key') !== 'your-secret-key'){
            // logic here
        }
        return $next($request);
}

Hope help u and happy coding !