SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac43f946f8410ae6788fe7fda91dc5c648fea724a353e9cb18989945a351d417' 
  AND token = 'jidN0wtLZnJlI9OCdqASVIBK6ougYkH8AhG3YaU1hDE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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