SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3eb4aef178bc3ab0b8bc314511f2a6773e3056fd73bc15c51f3f86ffab2f1829' 
  AND token = 'IT59TmKQkf8HXj8fMiIHB97KNJsCDz0EZEDMd9i/oeQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}