SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2738343be7f45e2ce666886e4145d11f9980c4e0d812b49d1fb7393e5a3e252d' 
  AND token = 'wMm5rc1bWFnv6nbkPqKulxkljGMHvjuTj4Q0FMVsEPY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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