微信小游戏 midasGetBalance 接口中的 access_token 指的是什么

Creator 2.x
#1

midasGetBalance：https://developers.weixin.qq.com/minigame/dev/document/midas-payment/midasGetBalance.html?t=2018329

我想问一下请求接口中的access_token指的是session_key吗？

我用的是cocos creator，我用下面的代码请求，但是总是返回：查询失败

{“errcode”:40001,“errmsg”:“invalid credential, access_token is invalid or not latest hint: [tk100729vr60!]”}

我可以确定获取到的wx_session_key是正确的

//wx_openid 和 wx_session_key都是通过wx.login的code换取的
let data = {
openid:wx_openid,
        appid: appid,
        midasSecret:midasSecret,
        offer_id: offer_id,
        ts: ts,
        zone_id: '1',
        pf: 'android',
        session_key:wx_session_key
};

let stringA = 'appid='+data.appid
            +'&offer_id=' + data.offer_id
            +'&openid=' + data.openid
            +'&pf='+data.pf
            +'&ts='+data.ts
            +'&zone_id='+data.zone_id;
let sigTemp=stringA+"&org_loc=/cgi-bin/midas/getbalance&method=POST&secret="+data.midasSecret;
//sig参数
let sig = crypto.createHmac('sha256',data.midasSecret).update(sigTemp).digest('hex');
data.sig = sig;

let stringB = 'access_token='+data.session_key
            +'&appid='+data.appid
            +'&offer_id=' + data.offer_id
            +'&openid=' + data.openid
            +'&pf='+data.pf
            +'&sig='+data.sig
            +'&ts='+data.ts
            +'&zone_id='+data.zone_id;
let mp_sigTemp=stringB+"&org_loc=/cgi-bin/midas/getbalance&method=POST&session_key="+data.session_key;
//mp_sig参数
let mp_sig = crypto.createHmac('sha256',data.session_key).update(mp_sigTemp).digest('hex');
data.mp_sig = mp_sig;

let resultData = data;

let xhr = cc.loader.getXMLHttpRequest();
//沙箱环境
let url = 'https://api.weixin.qq.com/cgi-bin/midas/sandbox/getbalance?';
url += 'access_token='+resultData.session_key;
xhr.open('POST',url, true);
xhr.onreadystatechange = function () {
   if (xhr.readyState === 4 && (xhr.status >= 200 && xhr.status < 300)) {
       let response = JSON.parse(xhr.responseText);
       if(response.errcode === 0){
           //查询成功
           console.log('查询成功');
           console.log(JSON.stringify(response));
       }else{
           //查询失败
           console.log('查询失败');
           console.log('errcode: '+response.errcode);
           console.log('errmsg: '+response.errmsg);
       }
   }
};
//POST参数
let form = 'openid='+resultData.openid
            +'&appid='+resultData.appid
            +'&offer_id='+resultData.offer_id
            +'&ts='+resultData.ts
            +'&zone_id='+resultData.zone_id
            +'&pf='+resultData.pf
            +'&sig='+resultData.sig
            +'&access_token='+resultData.session_key
            +'&mp_sig='+resultData.mp_sig;
xhr.send(form);