SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7e488ef879857a6437b19f5bdfebfd464ee7b7f76e695fddf5aebb587617734' 
  AND token = '9zM67vIULhDi6dj3JjKr9CZ6euMB7eALYSy/uUGJYYo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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