SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7dcc0bd5b8925957c0d094b7d11189371558970253875671a3b29aa0bf7f337c' 
  AND token = 'oN+LtvbgXajxgiBBOYUlBz6CXYGNZaJzfCSb82+/Iv4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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