SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '883c138e4ad217250af21f71e8215865be581f5887da9c06c520dffbbf6ed4e4' 
  AND token = 'AHvtb5WEsOm50hxrWDqQRBAcbrf/mNZc0UajIT5jVGk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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