SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dad343b589fb188e0f1f2e9c70aae6e31e49d2ac466b702f775bb5a4e42cef53' 
  AND token = '5+GGD+uV2nYwOq8nFoBoDvdgXMYQ9B6WOqKBdvoat+8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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