SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75b454f9369a48699058b3ea7f861caba81e0703488ee1b412a96a9cfcfb01b4' 
  AND token = 'ZGKvgiYM+oQFZSP3hp2YFDw9MJjTrzSvg6t8DoPMCtA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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