SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b12f4de6622c2f4b826a8e19fe8dfb9d68113f6403d9e1c27c44db1cf648e3fb' 
  AND token = '4zRPmp2NgUXyVMqOClifuUCfniLsrkIIkd85TPuFbw0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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