SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e388bd2830c833f0617cc05905d8379d2ee9cad73946e2ef9f6a75853ced6675' 
  AND token = '4w7jD4/oCHjMYbAU9MQJDJ2hB3IbOwEAVzK5YrvU9fA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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