SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a51ba68d79237c2f11cd236789abc4424c6c79589c91e419b7451dd3181c0887' 
  AND token = 'Xgnc0rGKrivdLYlVQGk8lRV7g53ibUD6W/O3GW+4mTQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}