SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76d04790193c77ede858373e005b6f13602fcf5d58d6ec72c7ed371a89116333' 
  AND token = 'ugyK3UiEbXI0rfB6I1SvoqgsZgYCuUS8qND9mpTH82A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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