SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f1b08c3d443622455524351ccbc2070f16f59cb3f8dd815f9b34519bb56b9c14' 
  AND token = 'KYLR11sqhPO17IwLL+RLJD5UhWN6rmO2646+7klpydw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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