SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab6868a68f7ad002799ac2248e13a2072d81fca5177c899f36310f974e206be1' 
  AND token = '12cUhRKqTkmlH0AQZb/tQVSOKDAJ8y5sBgTuqrBO+VA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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