SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be0a651574a83bcb7e32d99c80af22dc4d225d12f0a2d626e015c75b102378f4' 
  AND token = 'DmJEVvp2VDGCsK97HkZDVOaeACYODHvh+io3XPpDMQ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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