SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af5244d81ecf1d6683489b42d636330615035f0d1a2e4bd0d9e5955d2481d587' 
  AND token = 'Pr5J4m0XqenQB/fVGkmy+RQWsQQQLLxQiTUdxSMitb8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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