SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb94630805bf6a45d3dd7f1e0276f55b1b23c336a05c792eb9c369a41706d370' 
  AND token = 'rLO6oaPvB9sK65uJTdM2spnvm7f6nIow0mNjz2JokHI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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