SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '51602fdf8c3d96d8ca5ce192d90304b99ad9c6a1f3219f5ff9611ea6f9fb6c43' 
  AND token = 'Kh0zVJyg/IVet+GsisD38ziHqEvh++859bZ8XzWCqhA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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