How to know if my iPhone has facetime without opening the box

They all do!

iPhone models that are targeted for the UAE will not have the option. Do you know the model number of the device? As the Support Article noted:

FaceTime isn't available in the United Arab Emirates

MoMiGi wrote:

regardless region ?

Because certain regions have FaceTime restrictions

Of course you are going to have the same regional restrictions for services and not all cellular providers in a region will support the service either.

Wireless carrier support and features for iPhone in the United States and Canada - Apple Support