SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f438558f2e7be8559bd549a4f7d4737d87126a032d1a0e62b51124a981d8c6f8' 
  AND token = 'xlxzbvNZTATkuvGJQW+Gf5RgvIJ+Ub56e5bvQ6a/CZU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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