SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e01e1d279c49755f882aaef0f247c4628215639f9f76900c5660da95565e6441' 
  AND token = '1nJqExMAzz6BLe9EGkDyJvkvGgWXhvbHspujs3D0MPc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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