SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4eaf09df999d37573180a3b30c76fd8992f28a68e3f139c02d874229187511b5' 
  AND token = '358QtOzgMNRFxMVSPslLRXOXiIHKyzY8/dgOnAjadoM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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