SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5668aca120307b286e00ad225b3d25119d0a745b7226fbafe11f0400155c4c1e' 
  AND token = 'L00VsaW+IYD/BZefjdkZiXecLO/ZeudIK980wQUOyZ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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