SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6a8e54614460015d0fee5b20bfe87512121aa814f84b360a4347f577566ec2f3' 
  AND token = 'ZWx4/9GBlz+0hU0xJBc/X7Q5pcx3XfEDawr2OcNAAVQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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