SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '63631f3a3dc4e42bc941123bd0f628688a04ddbd6666d22c79f09b922895f349' 
  AND token = 'DXjqdl4GeSq6tSChS0r7A64YJ/JJ4ec7wxxConWWWEM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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