SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '834a3057d10402cf54f52e9b92cefb015ab462b8bb50ee52ccf368af201dbab4' 
  AND token = 'rwjt+0bQlFdlgtqw83wQ6WxpQFSJPYrZdZZ3BTou/G0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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