SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a876889ed9605f8e43a615dfb1aceb70c08edda6c89bb093119c45ca6445f1a1' 
  AND token = 'lacTfpE1b4zPoRYsZ8/hLFYs43hpKTKaDtfTWSAz5wY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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