SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '846e6bc56f5e40f68387228067348bd2563c54fbe5c593cdf61939ef29aa99e0' 
  AND token = 'rcVZxCJOBWpKUGSONbvG7yueiARi150YJo8eTBrfmBI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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