SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bdc18afc2a55839603fe86d7f32ca49135bfe9214928728871d23917249c2fd7' 
  AND token = 'gC5bUa7DPT6VTx5hUz6tdNpKzMzZYLTydte08f3/w9M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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