SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c347e724e770abbc2f0dce7bfcf7cb71817a6df29130eaedb6ed63194009df2f' 
  AND token = 'FXnneJZPjpuslUGMiTcRUS4mTdITxUvXWANRu0BzbOA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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