SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'c312b4528eff68c39323f2dd963121916ca361d28b771e407066bf0c7504b93e' 
  AND token = '57yW9T/5hCtvwso+VjWOn7z5IunoFijTX58ebPgu1PM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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