SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b3bf193645c516016428d9218a924e3b0c88779539a96b023cdca76f87129652' 
  AND token = 'vRf6KFcA69yisc9sqO4dYM4xN/dwGdU+8rxvf4TXwq0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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