SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '94c6337aa7715f4b1948878f4fd83d8e89c76b9e443fc0d8e33402a353849eae' 
  AND token = 'GzJAxAVsSnVwixFV7sfpBJ2/zv9WdYuv2AYnpCykwiU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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