Files with lcked extension can be most recently found as files encrypted and affected by one of the variants of Jigsaw ransomware.
LCKED file extension - Jigsaw (variant) ransomware affected file
What is lcked file? How to open lcked files?
File type specification:
File extension lcked appears to be also used for one of the variants of Jigsaw ransomware that encrypts users files and demands bitcoins as ransom. This variant utilizes different background picture.