SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '300db8ef4deec96687d42766defd977d9d0a4cf7728ef955d4a3b973087a0d21' 
  AND token = '2izVX2EgBhj4rTrwVWyqkRJsqqVAsKO94Xvo5GhtYvg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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