SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '69212bd4f87c0c2bcaf32c790868ee7df8ca865bff05848b1109fdbc9cb3e302' 
  AND token = 'PYD/m8diOnkLptFcEOaL6cGatMRl3D+XoWqrqAFbP94=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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