SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3af8baf441c8ebd16396363be416208ce5c103a24adeeb2b4014f1452745c01' 
  AND token = 'o9TrNKtBzj8HWNtXk+bZhoVH3waCoAopQu5u/TwxQBs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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