title: Access token for Microsoft Graph API is immediately expired
body: <p>I'm following <a href="https://developer.microsoft.com/en-us/graph/docs/concepts/auth_v2_service" rel="nofollow noreferrer">this guide</a> to authenticate to the Microsoft Graph API, and using Postman I can <code>POST</code> to the <code>/token</code> endpoint successfully get a token:</p>
  
  <p><a href="https://i.stack.imgur.com/Cpji8.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Cpji8.png" alt="post to get token"></a></p>
  
  <p>Now, copying that token and pasting it into <code>Authorization: Bearer {{token}}</code>, I try to make a request to <code>https://graph.windows.net/my-tenant/me?api-version=1.6/</code>, but the response I get says</p>
  
  <pre><code>{
      "odata.error": {
          "code": "Authentication_ExpiredToken",
          "message": {
              "lang": "en",
              "value": "Your access token has expired. Please renew it before submitting the request."
          },
          "date": "2018-05-23T08:05:10",
          "requestId": "f56bcd26-4314-41c6-81b6-e6540aa7b0ae",
          "values": null
      }
  }
  </code></pre>
  
  <p>How can the token I just created be expired?</p>