SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3caf11712903caf099f82a92bf52d7c15f3c9fc16462fbd6f33f5f83bc87b033' 
  AND token = '0t8metm9ZrYziwyCOCNWJVsIK8J7rD9UsqN2kqzQQ9g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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