SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cdd74debe198f1a98a1759214cb0fa326ddf338a5f396846dd95557257c81888' 
  AND token = 'CsRgxZ3uRQvmonHtrM/2Aysy12HGpN0fZ02MxzHZkhA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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