SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ba716471af3316644fc935a53018c181a3d38b9319c45206f11be650fdfe414' 
  AND token = 'ZMDIoobrmcR+8q4mk2TV7KiDQ5VHjrBmaXWhIQWA8L4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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