The Kusto Query Language (KQL) is the language you use to query data in Azure Data Explorer [1]. It's a powerful language that allows you to perform advanced queries and extract meaningful insights from your data.
To query for events that match the criteria you specified, you would use the following KQL query:
index==main NOT status==200
This query will return all events that are inside the main index and have a status field, but the value of the status field does not equal 200. It is important to note that the "NOT" operator must be used in order to exclude events with a status value of 200.
By using the "NOT" operator, the query will return only events that do not match the specified criteria. This is useful for narrowing down search results to only those events that are relevant to the query.

Explanation
The "interesting Fields" section of the fields sidebar in the Search & Reporting app will list the fields host, source, and sourcetype by default. The index field is not listed by default, but can be added to the list manually if desired.

Explanation/Reference: https://answers.splunk.com/answers/609626/is-there-a-way-to-check-if-makeresults-stored- the.html