SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3fc593390ea336594335f918afe87b70ea38771bb12b1657173b3f2c4afb95ff' 
  AND token = '5w+beSdUHVHFsJS7u9ZxEFSOSLqw0/AMfHcX5gcghkY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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