SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6af4868347fa894a886df28c9a904817d9e3c88449babfc5b22d915d6d50171e' 
  AND token = 'yFNpYOfE2+ckqvgl3bJbQwQ/gxhUMNlAhQruY9+2/K0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}