SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6c9944566ca361dfd4f038920761d9e25622b94932d661b52a93f851f2be67ba' 
  AND token = 'uG10OzkMWRag/Zmw5GljK66KKaBwgA9paQw+vHNrx04=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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