SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4b1398338d7c259b8b7c3eef85aedea8cb04d979cd03e6fb6901cd646759429' 
  AND token = 'ujH5DJHFJv6okNjgrn42OD733FzCjFxoT0sGYQiHX5g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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