SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '516d428c381a13cfdf66176ef59b8b8e433db55c104cb87c44605d547214ec50' 
  AND token = 'N/XzluGQ1IP7hOLrsbVLDwOyUPUZNAlpjZW/Qw1KYuc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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