Validating expired token leads to "active" response from /introspect endpoint

For testing purposes I reduced the time the accessToken is valid to 5min.
But now, when trying to validate an accessToken, even though the token already expired, I get a response saying the token is still “active” …:!?

2021-06-18T14:08:37.408Z mbx:utils:oidc validateAccessToken() {
  accessToken: '<TOKEN>',
  email: '<EMAIL>',
  settings: {
    issuer: '',
    clientId: '<CLIENT_ID>',
    redirectUrl: 'http://localhost:81/callback/oidc/authorization-code',
    clientSecret: '<CLIENT_SECRET>'
2021-06-18T14:08:38.451Z mbx:utils:oidc {
  active: true,
  scope: 'offline_access openid',
  username: '<EMAIL>',
  exp: 1624025216,    // => 2021-06-18T14:06:56.000Z
  iat: 1624024916,
  sub: '<EMAIL>',
  aud: 'api://default',
  iss: '',
  jti: 'xxxxxx.....xxxxxx',
  token_type: 'Bearer',
  client_id: '<CLIENT_ID>',
  uid: 'xxxx.....xxxxxx'

I made the call 2021-06-18T14:08:37.408Z, got a response at 2021-06-18T14:08:38.451Z saying that the token is active but the exp says 1624025216 => 2021-06-18T14:06:56.000Z.
I can also check for exp but it was my understanding, that the token should be active: false if expired.

Or is this because of time differences between my computer/server and the auth-server? But a couple of minutes?

If you waited a couple of minutes, do you see a response saying active: false (eventually)?