SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '33864aeb6ebd8528977be49f09507ba6d21aff5998287d2f4b3e3ae4a7683859' 
  AND token = 'aZzNzU0g7uW045FImRxAWQ0COqrPSMM8SKFut/YNcwQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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