SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cad014426dcea8f8d3114bff799f6065488efcd69d11de28ad55e76ee0d73bc9' 
  AND token = 'HE5tUfg+KUEGEmIIPw/yyBMJJ1IrRyzExCIPhgwj3ok=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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