SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '388e57f474729a58165efb91caf4662f4e9bff60b6fa4af5f6cf1adf9e50930e' 
  AND token = 'g+5CSeZRwg6MFbYnBSiZfCPP5ZgpFMnh+RwJz4a9ckQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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