SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5978f49742c9ffe8fd3f6bff2893fffe4993383dc22f68a0dbae373f6d1ed3ec' 
  AND token = 'Gr8t7zMlJ/zBlDpeBXHY6FqKSZiHwOS61a/QmJINZTY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}