SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '34c2c9aa31905972a8c03d4151e00d72fe418ba79837de99d8916b78d976e8b0' 
  AND token = 'DpzepvoVaxyqhiDvXLQQXV+O/NKFLkVjChYzuwY0d+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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