SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '682fde33e90925e22c53419229fa53f5587fa16ed6831336534545e11773eedb' 
  AND token = '6W6uM8icxEogZY3J6uhoPnqWBsi+5GLk//fxVMDKnU8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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