SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cef001d17d960780cdd5400d148a5a3d2b860b8070903c43eb7a0f24d7139158' 
  AND token = 'Mjt9cIgLfpAYq8ZaMS+VzrfifiJazcPrcdVPjt6rop8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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