SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51453e08eb186cf03c2210160cd316da5ca657d1bdfc72ea2f6af0c40b5fc419' 
  AND token = 'O2WDkfUwqpeXgVvCiEHwh7RzL9vSiwrktAAMDNGi5ls=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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