SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c9123790dea0e40cfa6f784827c0afb9468276f74de5b8703555aee39811359' 
  AND token = 'nxUNmaujYRu9vjVscaJjCt+5sj8hQX/bR8BsrGHoL8s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}