SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7fc17de00fd33a41e5c400762448da44bae32d3f223776d583ab4140695d7b26' 
  AND token = 'rZVekyfkuoy9ZFXmn+t12jP+nXG9nhm8VufiMqLyVh0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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