SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55ab057c792a6fa2af93afd23198df5d22d7177bfaae744c2cac61994098c9fe' 
  AND token = 'VWDjCPt6EnN6Cyidopg36tuXyG7Ej6flqcpplapIvyg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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