SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49836cf8a3cf74060934515421cdc00f8c806a2efbaed223afe589e0c9238a14' 
  AND token = 'gMyeaFWUUcXYzyMTVMSKWjDgsQUg/2m2zoWYlA6ZMHw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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