SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8bb04258421d938e4741db9349667e3d868c7ecb13a09ffe40080619afe43a5f' 
  AND token = '1lyBA0TUfvg1MUWXSgfFnC9UbChxsCkcOLR+7Hq4nqI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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