SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90423734166c49c873017285b7a67332a96d5d11aa83bdcc25d1accaafaee62e' 
  AND token = 'DEn8NgFDX11Lub6voi4BI1R7Eahp9YlPhz9+uuAqTWQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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