SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c7764298282a7ad9703a1989a9230a870cac812653de8d402f81a1edf948b89' 
  AND token = 'kvTyu+MpLWgImXnpoo9fjf6fDsWyw68WHHEFAdFKshM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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