Mandatory Input in Formatted Search Query Field

I have created formatted search query. Which has only one field "Serial Number"? I have to ensure that, the user has to enter the value in that field. How to do that?

I was thinking on implement in stored procedure SBO_TransactionNotification with Object_Type = "219". But I am not sure, how to enforce the validation only for this search query. Because there are 50+ formatted search queries are available in the system.

Please help