SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6a70cc66f2b3a022df214cbefde3d752da1f6e8c645f51509e2da15b996d61e1' 
  AND token = 'zp4RKUhvJBGWh9bQmWWOyuEVpfh5gFDh2XWoK6RBwyI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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