SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e115358ff2e2f0d89c9fb44d03abb7700bd0a19886e01fcd53c4e6cfa29c349' 
  AND token = 'FD/lVDwAGppbVfw69l88AR2ZuuE8vzeCF6UKRPJ+Qkg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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