SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b945905d430d9c3806a4651f74b90c5fee3498d39a69859e3c657ba71e50199' 
  AND token = 'DAc0vOiUNHEK7onQ6SGbNkv+OzSnXiWpXki8NiFP5fk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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