SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2d7641eb67429369238f4c90e00e798267603612c48ff4fc04616bfa0a29f72a' 
  AND token = 'J586IsOm1XyU0XFEj6mevsPg2AtqOATYrCHnL3RbjzU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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