SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '789245bd0537bb7de582e7808471cf13a68568c44f803f52565195df909d6f5c' 
  AND token = 'WKEIW/taHZnD6FbTseQzFI8g+W5dRvAVHYRUkMgr28U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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