SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0477a383d4d978629c09fcb1347d510ad5987b36886090a1506484a8c003a796' 
  AND token = 'sCG90cf8wF+DSiWcenNqMFszMCGyxvLlvPeyslT5SWs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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