SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a6ed0b35cfe7dd57f2f9af8cadc824fee720c74e73fc33aba1c358e08918465c' 
  AND token = 'WxVDHzObuGqxFMZpuygP3qxqgxvLQW6Y//bwHKrihqg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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