SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cac0f9dba6fefe1799d94388a284572b3d91f10cf2ce6f17991f489f4a0c81e9' 
  AND token = 'WOHTASnjI58haWaZ3gs5RgMekTfXBr9tT39sGfbHsLs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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