SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6afd2be4a5547395d03c8b8fcddc368d3c6b68d8da4d352705ac702f3dbd3508' 
  AND token = 'JPwXAAJN/eK70rLtxWs8Dcw1zh7S1IHaEj2Bxy9eb8w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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