SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '581b8e0396599d75908d0ef5c9915a52a80074622015bfce194c8849aa77a03a' 
  AND token = 'BrVvH/Bf/iQ3Tv5YMpEBl3v7XaUzpyBwmWXvNwEiEp0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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