SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad8c66a4a078ac378ddede7869c326a6e632b7841a13883131f9fa40d1be8dce' 
  AND token = 'F3kwh2Mekqm7AeZJrd4MkZCZ5WAtfatUt5eseXAUm9w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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