SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1834949b2d0043b15c53af30615ecb7ed9ac074ba2f6ecba9fdee7b8237e143a' 
  AND token = '+8NQhI5BrgmI05MgqPQo7nZVBVvn6FUJzHmRpsu8nfc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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