SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83f78885ac940f32d250619895b2e302cbb0bfa7fd68930e04d57a5220651cae' 
  AND token = 'Oql+EMo6tCQv8Xnlr/VRS71UTf5rSQcpRj2ykSR3gWs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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