SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9fd62e98e89ef995cc448597e9f382bb7a36d9c9b3d587280075e00f1a8b29f' 
  AND token = 'fGYoa6cvOLhhZQsaOYdqOVVFRkhRg6gWU7ZlZnPM4eQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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