What exactly you want to validate in microflow?
You can retreive the details using retreive activity from the excel sheet, then using loop you can iterate each customer and check for the specific customer you want by customer id/ private key.
By this way you will get the customers you want.
Hi Aqibjaved Badekhan,
In excel importer, while you create a template , you can give parse microflow. In that MF, you can validate the object and can do commit.
Hope this helps!