SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb1f1f985fd3e8331faa2b8b75a6c44832c082259312bec420214d43cdd4b669' 
  AND token = 'KtvJzFlxlHplRiyYjn9Pawz6plQJPqnZ1lmHwziO5bM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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