SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e813ef98004130885d895d42ef520cf7951fe4fb7497aea4093e4d152b0197a' 
  AND token = 'K3P6VeDvPF+H9LVAq5CAieLg384mdyDY2OVmyvmfC/U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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