SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a5321de34020f6829c873784b2be17384a513c55772501f60fd8bfc18fffd14' 
  AND token = '7A1E4kqJa0vIZ4WDjB07E52ZqUDTb45aaInO7VB9nZQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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