SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '777a9b6f32b22fc144cc4dab3512f85cd68c4283add6fc1ca774e1316c1040d9' 
  AND token = 'TNmt8t91HGDKnve9bVWeTmYoGRaj+Lws+jBhf0Cy8bE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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