SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d39da18e42e540a4beadb48797c8d87d802ea858bf7dd502b34150d1e12cce7' 
  AND token = 'q+8VFjsJYCoLds8LfyI8zWYCbLaDZJsUrcSUdpxFixk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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