SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7adf424fa552b6dfb3e0734e1d385178dfaa45ccf6384217d91d25e0770c309f' 
  AND token = 'ncHAPUXbLHGoFiez8P4IXNIMkOgIkuCd41cSu15/EPI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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