SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '88e1946bddd129cdfe29f9c18a550345deecbe573a0230d445b7054f87a35387' 
  AND token = 'yQY1cOvy64dBYqz8O3srjySs75PSLZhVIUmpr7tcD7U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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