SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '246e43d67a55dbeb01f14800f16ef6d16f1234a21b3b7025f4262fe325795738' 
  AND token = 'erDGYmP8MFxTv/aZkvzNmhYxQbOgfg8VhIxxupLi/Zc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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