SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2fde71d11ff870fa415d36d4a91660a991abdbbb93f777394542bc67ba61bd2c' 
  AND token = '6XwZSYLTeYLESM6Fbuh3hzSw20sADOVIYM8ClgjehfU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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