What I want to do is have the Arduino automatically detect the key whenever it is within a 1-meter range, and then check if the detected key matches the one programmed into the Arduino.
I'm thinking of using two Arduinos with Bluetooth, one for the key and one for the system, or by using an RFID reader. Anyway, I am not sure what module is best to use, I am new to Arduino and open to any suggestion.
My idea is for the key to have a unique ID then the Arduino will check if it matches the key that is programmed to the Arduino.
I moved your topic to an appropriate forum category @devopp12321.
In the future, please take some time to pick the forum category that best suits the subject of your topic. There is an "About the _____ category" topic at the top of each category that explains its purpose.
Why not start by telling us what you have tried and what the results were. My main interest is in the RFID portion, 1-meter I believe is out of the range of the low power units therefore you will be getting into some expensive units. What have you found on this?
What type of battery and how big is this key going to be.
You should use something like google and search each of these ideas to see if you find something that you like. This will probably not be a one evening endeavour.