Keychain login in Keychain Access Utility is Grayed Out

I had this problem as well and the simple fix is as follows:

Try these steps to lock/unlock the Keychain: 

1. Close and quit the Keychain Access Utility

2. Open the Terminal (Finder > Applications -> Utilities -> Terminal).

3. Run this single-line command to lock the keychain:

security lock-keychain ~/Library/Keychains/login.keychain

You may be required to enter your Mac user password. Please note that its input will be hidden. After you enter the password, hit the Enter button. A pop up may also appear prompting you to enter your password. Make sure you do it in both the pop up and the Terminal window.

4. Run this single-line command to unlock the keychain:

security unlock-keychain ~/Library/Keychains/login.keychain

You will be required to enter your Mac user password again. After you enter the password, hit the Enter button.

You will be able to see the padlock closed when you issue the lock command in Terminal if you now open the Keychain Access utility.

You might have to issue the lock/unlock commands several times if you don't see the issue clearing up at first but it will eventually.

You need to leave it open, otherwise you will be prompted to enter your password every time you do just about anything.