SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d4dbc9516cfa6fd2f6e2401343b478db7cbd3bb85f555249d69703718eb0dcd' 
  AND token = '6H7YapfBqYV1OdfsAWEL6YnzgRlCKjZ/rauBJUCrUBw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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