SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb6db1df930960b79b5650949c806c2403474c846ed09565e7482bdb929b1ec9' 
  AND token = 'pL6XAZQ726MK+CCFCYH5akOjijsay6kUDEPzhI3+kHc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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