Here is an excerpt from the book called I’m Right and You’re an Idiot (by James Hoggan):
Those previous frames kept climate change at a distance for many: “It’s happening, but not in my state, or my city, or to people I love.” It’s time to bring the message home and key into the faith dimension, national security issues and business sector, by outlining both risks and opportunities.
In this context, what is the meaning of the expression “key into”?
To key into something is to focus on it.
From The Free Dictionary:
To pay close attention; focus: improved service by keying on customer complaints; keyed into the main points of the lecture.
In this case, the author is saying that by focusing on the faith dimension, national security issues and business sector, they'll be able to drive their message home to people more effectively.
Key into means to grasp or understand, informally, to get it.
https://en.m.wiktionary.org/wiki/key_into
The phrasal verb has a variety of connotations that resonate because of other uses of key both as a noun and a verb.
Like a key fits a lock, by adjusting the arguments to make them fit audiences experience, opinions, or circumstances, one can engage with them fully to achieve the desired result
I can't be authoritative here, but I had always assumed it was a reference to Foreign Keys which is a SQL concept. A foreign key is a pointer to a specific row in a different table. citizen.address_id might be a foreign key into the address table if it uniquely identifies that citizen's address. It gets used as both a noun and a verb.
As a verb it is used like: "We could key into address to get the citizen's country"
As a noun it is used like: "Does citizen provide a key into address so we can get the country?"
It refers becoming oriented in a different space, or to an item which makes such orientation possible.
I'll note that "key into", in some contexts, could be used to mean to operate a digital keypad in order to gain access.
This could be the source of a metaphorical use.
