SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f548fd96137a676df1e37936908f8309218acc5eaf5efacd79c2015db182de96' 
  AND token = 'LcZw8vT7HNq9ZJiKU7OZC6Qo4hRm5yowPgslnq/IRus=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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