SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a43ab0ccd45b8662dd3b6bbecd722482bb3e26d84e361752f556ddce096b7c43' 
  AND token = 'Duq0iTw9ildlFyx8j4R4ezLEycK0IdvVSmXhja2wnSI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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