SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd96d9130064fb53abf48fae80003278cf0dab0f155c0405eba6d502959265834' 
  AND token = 'WktywiDy9QAgxmUZxd/tLyIIqMxqkQafdWfIxnKakwk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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