SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38f75426e0d07b5444a5cfb897af76546e86c3764aa908f0ac12b4b1f32afcd8' 
  AND token = 'AmC4gg3Ql+gXmnsUUSGR13PDNR9J8AGyUbCbZ2qTuUM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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