SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '1b06ee1f55455ff208fa90d068f8b5ef994fca8267800e623fdac6f63a20f42a' 
  AND token = '2/frBLHi0EYbli0CpLcukNZAYFC4Z/d8OoZKnmw56IE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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