SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18f4452d1f03687749cc0e26a214b6f2880df2f5bd0385bdb83ca17813d168f8' 
  AND token = '/YH4BXzHKKyjAIBt1+7MADjKTQh9g5cgay2vTqGg4sU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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