SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a56f4f192393781f71f549237ea36eb3e58891bb68cb02b6826ef70f2d3aa548' 
  AND token = '3N8St7S4Ybx1syLSvGCod/TU0+Ib4jW0bJsGmBd7Rsg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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