SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b81c6896f9bc455369bb38d12adfe74fdacfcb6271caec4645422af50fc65603' 
  AND token = 'VQ6iUuWza3u/rwRJ7AVUhYXI4hDs6u2hm/mqrbSCZDo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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