SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50580435616ecfc2c6d1f473858ce1554cf699ab8b27664aa562a653b359c84c' 
  AND token = 'FW33prH/CLihJhrVDLf4oBdw0cEPg875/bSq0IsFkyY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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