AWS::IoT::TopicRule - How to simply check if a field is present?

Imagine I'm receving messages like this

{
  "Id": "ecc-AABBCCDDEE",
  "CmdRef": "ZZZZ-YYYY",
  "HostId": "ABCDEF0123",
  "GetSchedEventRequest": [
    {
      "St": "2024/07/14 08:16",
      "Dr": 60,
      "Ty": 0,
      "Rb": 16,
      "En": 1
    }
  ]
}

I need to create an AWS::IoT::TopicRule where SQL is allowing pass for each messages which contains GetSchedEventRequest. Is there a SQL syntax available ?