SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4acff938673ca8a2d152fb2de5096205681e458bc572be15d0969ecf4bb95c8c' 
  AND token = 'LBZRy9bkWqFhaKVCsdDRdpi7bLzuaO/IwE+jcwoTYAk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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