SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6867ed94303a001f5f5899a0de03cf08ccee87adef52766fed84ee4cd28a26f8' 
  AND token = '6ZdaicFcEp3aridssQVy0KSOFlNCXyYFxoKOhTb7GAc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}