SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77e808f7f0673702a3a7f4b8b012c9434cd9a314a9e027f0ef8502d5be4f2155' 
  AND token = 'WnzAd37akVBf19fnt2Ul2VQjK1VxvcHnRpKcayAzjWo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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