SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2e2374f848b5942bdfe01d375e8c4368960a6fe7972e03ffb52ab9c345f55a84' 
  AND token = '5YwDh3tTiktPjzuHU6rZM9J4RgJRE5actOPFzkj+fys=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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