SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '30db5648718e4f64a30f86dbf5ab3c1b9354e32bca8bb6f42ddb6e68271ea53c' 
  AND token = 'K7/QjKDRrXK2L6tXOpFQwvjh/HiGC6guNree9UkDMPs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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