func (f KeyFlags) HasLocked() bool {
	return f&flagKeyLocked != 0
}
HasLocked returns whether the associated key has acquired pessimistic lock.
package kv
type KeyFlags uint16
const (
	FlagBytes               = 2
	flagPresumeKNE KeyFlags = 1 << iota
	flagKeyLocked
	flagNeedLocked
	flagKeyLockedValExist
	flagNeedCheckExists
	flagPrewriteOnly
	flagIgnoredIn2PC
	flagReadable
	persistentFlags = flagKeyLocked | flagKeyLockedValExist
)
func (f KeyFlags) HasPresumeKeyNotExists() bool {
	return f&flagPresumeKNE != 0
}