SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd2b447d47dffcb05ad7490338a7be21b753e5cd3e0125438fa7321b8c385d06e' 
  AND token = '991el+gXGie3ugwjFmLOwajKgRv+CH64IWlf0zvY10g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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