SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c78016ddbfe60509bb591e373b5f56dbf036b5619b713a25029254ce767bbd8' 
  AND token = '/ol3IHV+JPdtzwmBiB1ynEhhYv2R/me1GZ1gGSBHIVo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00066

JSON explain

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