SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7f438953a4625ff7cc779f8678509d170db9396242db52c88095102787adbe0f' 
  AND token = 'NAyhZEs6Q31BM5tlG/DwOtBH2f/usZMTMJiZon/YEfA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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