SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd9d8618cb40407a57e62fd20400066676c113b7b4991595fa5fb92338a0b9811' 
  AND token = '2lrYuPlUPKlg5wBpzZtkmA65B6tK+mK6zzZ63QTF1uA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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