SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e671f869bb8700af9bdbaceafcf9c0311970047d9acc9a6a15e51af93a61f50' 
  AND token = 'kkt1/1woTUkhQi5s1qGJfHcu8CUrRUvL//6nVJy1FTI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}