Within a few minutes of emitting a log entry to Application Insights, it becomes available on the interface for querying. To do this, open the Application Insights instance and navigate to Logs (Analytics) on the left-hand side menu (1). This opens the view shown in the following screenshot:
Here, it is possible to write queries (2) that search the recorded logs in Kusto Query Language (KQL). Application Insights is optimized for handling large amounts of data and most queries return results within a second or less, even when searching millions of log entries.