According to Google[1] key in English is from an old English word of unknown origin. It also doesn't mean it has to come from the word of the exact same meaning

According to Google[1] key in English is from an old English word of unknown origin. It also doesn't mean it has to come from the word of the exact same meaning in its origin language [1] https://www.google.com/webhp?ie=UTF-8#q=etymology%20key https://www.google.com/webhp?ie=UTF-8#q=etymology%20key