SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'c637ebb02846df20d77315115af42d0f550eed4f4595259d8bae6ef855812f93' 
  AND token = '/khv25Q/fJMne9hIsXXVp1K3rpDeVYOb0lPiFWO/ekQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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