SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3b9d4f2583c0721642ce94fb6aa556ae6c2961d1a76926c89eed4252a175154' 
  AND token = 'zbnKJHOS63WnYOJ6jUQ/rKpWIAhKuSXvVxXXUtq3WW8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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