SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8bbfbc15b91155b6caa596934e7c136870da4261dadcc8b8f499290984bcac32' 
  AND token = '4oZM4zwQWTAU8YaXuOMojvWhYbTtOy1I1jQgN2zw/nk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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