SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7a6dc0bb06382992cd37ca6d2239e4f20cf55b3da8e3e92a17819058baf928f' 
  AND token = 'wMgjp9HHrCvtU+Gc+1ZDwdvCOjj6jrjTfC/PQezfPJw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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