SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc9379b0fff85182092a7ba44a4efc66b572f41ed296141df7f4a3f805b5003c' 
  AND token = 'CdQU33aU5XUwe1ljHyrBgbly3jlhHhgMVKvQUZWC/Dw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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