SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'cc3557d51103a10bfbc474f40d11f0ce2535385bb8a3a2d2a8632b8c4acff409' 
  AND token = 'kE2GaRbn2VnzdUX2xUsXkA7Xsy+yeYPOSB5tuD+ETYs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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