SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f1f395f064a2dfdaf745247620b127cf697ee4e95e416cd718003fcb56ee5833' 
  AND token = 'aziu2cr/J5jYFbtf5hguzadP1uFsb1uX+W0IBkj0eMU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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