SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c49f689a12d97e0fedcc23f05b8f919eeca979f6595d38181881668a142216d' 
  AND token = 'OdvAKp58lJnn9/JxZ3XlmzMTG9Zk5eRMWeFZFKjSAeg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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