SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8d303ec60288a717f2eafd838193c6fae161c228088dd23728496e390118aa4' 
  AND token = 'HCzV5iFwqZTc70GP1lJeaVRkZAyffUqfqqHl/updmXw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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