What is the best storage for data without relations

I am developing a simple web application based on Spring Boot, which needs only one table (four columns inside) of data without any relationships. So the data model is very light, but still, it has to be store in someplace and cannot disappear after the application reset.

Table (or some collection of data) includes objects, where every object has three one-word strings as separated properties and one boolean property. Two strings are immutable (name and surname). During the application life, probably only the boolean field will be changed in objects. This change will be scheduled and executed once a week.

I do not need transactions, and also application is not multi-threaded. It is Java-only application. Queries will be executed only from scheduled task. Size of data collection will be keeping at the same level. It also is going to be very internal application, so we do not have to keep notice about some problems which appear in big infrastructures.

Which type of storage should I use in this case? Some NoSQL databases like Mongo? Or maybe keep this data inside some file stored on the server-side and read/write to it?

Do you plan to search thru it?

If NO then a flat file is the solution.

if YES you will need to index it. So better use DB for that.
Any DB would do!

Advantage with mongo is that one can change the schema on the fly, so perhaps a decent choice in your case.
Just remember to index the collection!