SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '94c59c5dbb92103aabc194a55ce22d6049d87d497daf0d2a3a74de67ef48aa13' 
  AND token = 'lGmxn8jMtl04sQVG1a9O9EimQvt+izdvwoZkgYaLslg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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