SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b7c95bfea2204350536da67e46c7a92c874b9ed5400650094fc8868d7eee793' 
  AND token = 'BxTenMInAQMVNwA1g+dp08XZI+2zR+0WnXj2h486Uls=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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