SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7f63658210f713333344045487ccde91debe47296abcf2f83529ab40f9b15a4' 
  AND token = 'WcyuaE3ToBnS0WljVaFRlg6WT8sxC2/mqkTtA9N6AWc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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