SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7629afb82037f2aac78bc390011b012026167b3288f1ba70a844ca8f9293ab35' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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