They've done the exact modification that you're proposing (placing it next to the door, rather than in the door) at my place of work.
What you're looking for is called an 'electronic strike'.
You cut out the area around the existing strike plate, and wire in the electronic strike. You'll need to feed it power, and a signal from whatever you have to grant access. (in our case, the card reader, plus a motion detector so it'll open from the inside automatically; you don't need the motion detector if you still have a functioning door handle from the inside)
A quick search online suggests that they run $100-500 (US$), but you'll probably want to contact the manufacturer of the card reader to ensure you get something that's compatible.
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As for 'best practice', much of it comes down to cost vs. what you're trying to protect.
The advantage of the electronic strike is that it can be hard-wired for power (no batteries to replace every few months), and you don't have to worry about cable bundles through the door or wireless signals (for auth & logging) that can be intercepted or interfered with.
If you're only protecting a single door (so don't have a centralized authentication server), don't need to log each person individually, and don't mind changing out batteries once in while, you might try looking at the locks they use for hotel room doors that replace out the existing handle + lock mechanism.
The lock barrel is known as a Euro cylinder (there's a photo on this page showing Euro cylinder locks booth side and end on).
The numbers XX/YY relate to dimensions (in millimetres) of the lock when viewed from the side. The dimensions are measured from one face of the lock to the fixing hole in the centre, then from the hole to the other face.
You can remove the lock, measure it, and replace it while you wait for the new one to arrive - it only takes a matter of seconds with the key to remove the cylinder. However, the bad news for you, since you say that you've not got a key, is that you generally need a key to be able to easily take the cylinder out. As you can see in the top of the photo on the link, the cam is slightly offset when the key is withdrawn, so it doesn't just slide out once you've removed the fixing bolt.
Best Answer
Yes it does seem that they are available.
That is a Mortise lock-set, I did a web search for "smart mortise lock" and found a couple, the question is weather they will fit your particular set up ( and can you afford one ).
You will need to do some research. Most of the ones i see are set up with the latch on the bottom and the bolt on the top but yours is opposite that.
Now go forth and conquer.
If you live in a big city find a dedicated locksmith/lock-set retailer.