SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c648397e3aeb855a0160eb5d9d8983f42547d7e4f95a5d833c7e55abddabc7b8' 
  AND token = 'k/K98vMOibgZWy3uYjVhT+0tmPlHULGQZH46JADI+7s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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