SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e80128e934f4cc1f842fb5b4c545d260293ee27f84d8564af795c4da78d82a21' 
  AND token = 'cUlLLCnMotebCDrOyL6M1eOnyizFFCo2/OCD5pTa75U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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