SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6d8cef16c5220890d4920685e0bbed3a191250eb337609c8c3d671c3e66e1e6' 
  AND token = 'oupHO1ld2UvYnbQkv2KT7nYo3D9H6DwRLgGu0RqVYfQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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