SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ce8e1615d996a6b845eecf6b5624732533b0b88ebf6ec3009d831d7d070af8f' 
  AND token = 'xx9aVGcDlUBB7GTWKWptdz2QPu+/xUuebYOygM179zw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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