SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '0d8244dbf76a03218f03e1a771c15d88f228443bf0fdda7b80695f11abfce708' 
  AND token = '7GChkBDap4BJ6mCPVTLu65lVuqDB+gDga2rqvBAGcHw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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