SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51dd9adb5841a0443c2481b3d340b1a9c27bad914890880956220f025f120247' 
  AND token = 'BVKwWpXK93ofkhdZ3Ecq7UFHov69UFVh+UiTnuzFebk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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