SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a2518ac2691ebd37f05baef814c32008dad26136abf4ceb950c2828f5c47178' 
  AND token = 'snmbswK908zkcKhKqOrnnbGBTcVJTMp4U3VYhLcea+M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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