SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '646febb767f2319ae63033c1d61179688a90537211a5a119526afc33ef47eda4' 
  AND token = 'OPaA0knI1w74GNn3VZfsx5VLytAO6iCkcRGmzZ4cQdU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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