PHP GuzzleHttp如何使用php变量发出post请求？

如何解决PHP GuzzleHttp如何使用php变量发出post请求？

我正在使用 guzzlehttp 进行发布请求。它本身就起作用。但是，不能传递任何 PHP 变量。他显示了错误：

变量$令牌被使用但未声明

我怎样才能传递变量？

$client = new \GuzzleHttp\Client();
$token = "0x75ebaa7d3029d55fb65508b97bb9b205a6c7af01"; 
$response = $client->request('POST',$graphqlEndpoint,[

  'headers' => [
    'Content-Type' => 'application/json','X-API-KEY' => 'xyz'
  ],'json' => [
    'query' => '{
  ethereum(network: bsc) {
    transfers(
    options: {
desc: "block.timestamp.time",limit: 100,offset: 0},date: {since: "2021-06-08" till: null},amount: {gt: 0},currency: {is: $token}
    ) {
      block {
        height
        timestamp {
          time (format: "%Y-%m-%d %H:%M:%s")
        }
      }
      sender {
        address
       
      }
      receiver {
        address
     
      }
      
      external
    }
  }
}'
  ]
]);

$json = $response->getBody()->getContents();