SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '039733ca455070b19da79f9a10dd706a4a046315b17595289d7ef30cba820267' 
  AND token = 'IkQc87D0sOTnAlL1wa/2GKWUKVrPuAxKsdPFBimQlVo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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