SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9683c261a99b7ca4fb6c4a2a9e34826d240d7df3b24a15603e57c26fe733b827' 
  AND token = 'lBlhOXvveFUiJ5bS+HocibP1RqPzZl7oAQgsaHzk4Oo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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