SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '143be03e39b4ad30f2f59dcc71c542e9279bdf4d31c1b762f0e956f650367258' 
  AND token = 'vuGAP7pJ1/1LKOHf6g1Nm+qjyTcLOExxmY1hrK2sudk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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