SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29bca40594177422c7c27f722eff236dc12ab52a571f68e2760209af45b51bbe' 
  AND token = 'Zz/ozAT7hSxW6Qrhxwbyk7as4L8RKdmdYBBoqHE0cIU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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