SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '0bf68c76a36213833a088620286650b785fa6cb35f34d54c9cf3b391f256e712' 
  AND token = 'mNA1maIIrfYqY87h0eGLEh2qy/mmS+EKz52CXTa4G7Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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