SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4defe4f37999d65c990f58222d5bb098d621fe7d638f2fc13f46ffa1723b16e3' 
  AND token = 'uMDiDkcvXTwoMCtVYSVs08TQG7vwjgg1tmmKleQm9+I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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