SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6c035b185328eb65a13ad90f4d2ba2a1d153ea606b27b68c1143afba4587208' 
  AND token = 'Xx3rXA4FRXLtaewcP1QkiUhF65roHqcwtv3osqDZ/+Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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