SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab64018e2ad29c434761b7549631e50df57b031e2d79a63c2f79e2c38d579577' 
  AND token = 'MiDlflEF49+xYDunfCvo7iBJbWRUqoocBLd5VjLR98A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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