SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6c48f668f235f131af5cd995a0eb1d699cb578adcb0dad391fca9ec8d2f1c99' 
  AND token = 'qKOP2Mr6lv/Z2TQFfVBlXP+cRFzURyPSdwe+seY4DXk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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