curl --request POST \
  --url https://api.hubapi.com/oauth/v3/token/introspect \
  --header 'Content-Type: application/x-www-form-urlencoded' \
  --data 'client_id=<string>' \
  --data 'client_secret=<string>' \
  --data 'token=<string>' \
  --data 'token_type_hint=<string>'

{
  "active": true
}