SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cc9f5e9f466b974e27025a7029aeee46f1f50699aea0c3859afa1e061997ef3e' 
  AND token = 'D8f/2YOMQtmWJ2HEb7KnuCFHZZKeRFwuVmw7C925ob4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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