SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6e088647095cbe454db08f15af59507b297a866427c0c1894568e07a5415b36' 
  AND token = 'WLpIgXvpGvEWG+S6FfjVX1PItG36NACFkoODxjNc6DQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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