SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '474990fd4d44c54282fa646ca0fc5fbb74eea53d45b67f740163b3c9ea1181c0' 
  AND token = 'cK/MGAOuOLH+iv8xvO4J1X6WjzRvIAKiXzQEoIHKBgM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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