SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12c11a820ccb542aa7e58298576ce5e8a50b4d65272d91dd205c24d246cbee50' 
  AND token = '1YERwRgFRgg/xMaraiuWFunqtO4lRwLMYMJUaW/Y/Ik=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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