SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76cf849a148fd0c8ccbf5d6b886a9343acc7817b133dda6a444be8d42e655132' 
  AND token = 'zTXWUKqIzwg8NtofrYBso0gd1qvZTznXBtWPNizxvvw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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