SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0bad273e065f52192ce2d24d6e03c2408d20e9e4a3ef8b976be253d015b34f8' 
  AND token = 'ttVpRzPjrsgqKCp37pj/KLT0FwadMTtwpeTIDlsWW5g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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