SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f6814861fba9a00901f9f92f06042887e3fe592ad168098faf2069a18a18f70' 
  AND token = '1L/9BPrg0XWdPdOGaMwEjcVxvTTgFxsukVxqLw7t5f0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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