SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b44d929f1fc43dbd9bda399b56eda52dad3d1bca8a9a675de40f1971670d4d1' 
  AND token = 'z+6mdC1K1T+6VN008221OzxELekbPmoB3igz8uMAF6A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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