SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8d49ef38f6d967ff3629059f6e03537035e74142c2afb42d4dfabb8f2fcd36d' 
  AND token = 'zxmASRzdTK4nghiG1C6If/IVjhqCyLZ9wZS461VgvHY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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