SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a3598955edafd303d32632d026f31ed571e1bffa99ec574442518a6e5b160b3' 
  AND token = 'vlCOl7NJ2JSBicbbd8K+jvnd7JuXVWggdutwiuNfrbM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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