SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71d72ebb630dbd0dfade926c08801912627beb78701553c8baba3e313a5bed9c' 
  AND token = '9IfDDzfF8p9tU5MlvuKCRKOH8S75qRpHQDwgDHhsglw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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