SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5db1f06abeebf16bce73c453a3029dd059f73f8d2f234ec04a98b43a3f8a6468' 
  AND token = 'YQgNq1BvPWPkMLeMFP4cNnurBmBiDZzq5haBjMEH7W8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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