SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3419981ec5ac05dd215692206f15139a086478a3244d65c6e4fb33a6ea69710f' 
  AND token = 'uZ592HKvZIz0mgqv3IUcP1bqfy1mtxK58ihjYi+5Co8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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