SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c4c7f5676e069385339048dd118e43609ebb7c91c0aca3bca7a94f3c5ee8178' 
  AND token = 'LNxdxyDphkPqnQoSw1g95vQ3hfSdDB1YkphnRlZLB+s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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