SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a68097f666b310f200746d1f5b9ae19a49dc5aa45ee6560d690b9eda46bbfec1' 
  AND token = 'rSsfBYnLIGM7rxuypTaFbGwNzy7Zwz9F4z+o+tviRUg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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