SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8cbf68545005217c7c17f436834f18081804b8d2b8d40e62cc63ef346ac87ad9' 
  AND token = 'jOhk4tERwsidoWcVB0rkarTBjzSPvpPEUSRVpjPBw+A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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