SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5835603df7f334ad52246d4de1ff31c08e86994c10d4e80a9a3ed4bb14d56e7' 
  AND token = '0wUt/QIjG/LpsUwhjAbqq1YPCnSvZoqu4L1VtifgEos=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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