Detect if my ANN model is overfitted
This dataset presents transactions that occurred in two days, where we have 492 frauds out of 284,807 transactions. The dataset is highly unbalanced, the positive class (frauds) account for 0.172% of all transactions.


I guess your model learnt nothing at all ;)

You should consider some form of resampling and using metrics that can handle imbalance.
This might be a good starting point. You can find bunch of similar threads here as well.