SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a039bf37d200b894471fb5220575a198331f5b250f398e882e85e697292264e8' 
  AND token = 'drAsI92kyLcbmbafVXVjegswQWH1p+lx7Tjy3ywrNXA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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