SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '944faf890f5b5760001e6865d94e8dcd0e379363f119eaa939668058440c1ede' 
  AND token = 'o7IKFOFt5jPw41dDY/q8ZbZkRXvsUNE2tPxlXx1vO58=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}