SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c63018db164dcd9b3a7ed3f451be499193fcf28f3e1d4c69a0613a9f5bd7a691' 
  AND token = '2jJRMJVb0f1kkm2XIFx/QrEy/+B8agGiWXXwyYAVOrU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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