SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a49646dfa6d4ca0a144645e289b8874291c117c8d0f9328668df40a103e7359f' 
  AND token = 'tvSe8O+GLdLS7D/F6I23DnDWaWRazNqMsHPsJuWRycs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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