SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0543739c2a1586c940afb41c4d73be8ee5cbc91f39cd3ae8758a5ac8d7dbcc64' 
  AND token = '56YDaPeNYt0Ym5VAEJq3fuJM24LABQF6J50+/+jDp0A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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