SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd668d9328ebbf0dfb75717b052a43d45fcc0c87c3b1bac6a839930dcb594d691' 
  AND token = 'hJNBxQNfs68+fqoCLajztErmVThNDz0K9FTOXvDe7Dw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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