SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb709824b8d073298371f3fdabced4407421548cbbe23686f197dcc588e86828' 
  AND token = 'UJVIOzOLC60Oz5G9A87cdysLqiyTVyAd4TveQwnR4JM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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