SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51bcb4321366b73622510e530fa0ed0179acba80f7aeb4685d20f2014c58985a' 
  AND token = 'VIOpojBlUMTEZB8e6O7q+RG+VxDHwLRVwjvYZ17cewk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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