SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4340320d87a8fa9f5b31997b1ad0f6b6d05f6ca51d04985d540d76a394c0da86' 
  AND token = 'JDqjdSZNncgHciea4Edgto2wWaWreSySCB00SZlFCAw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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