SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '210c681e9099df30a77632b8d157b66495d9bd20361cf184355c59778c433b57' 
  AND token = 'YF61TKUXPTOwKKTigxM9zqkB7NtkgHfDpIAmI5jBZCs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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