SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e5a5f007060ca60b035e59021c6732429b25251864a8aa5959a04d29e754d4ba' 
  AND token = 'kBMpIb3xm6yNMyZZWjezgDCRflxuaiCbJ+R8WtooGw4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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