SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4ba8445332da17031adc774f3f834dbab50cc0e81e07cd90b85eea72d50a2cb' 
  AND token = 'iZOInXTCKcjTSNNrzoyiFiWar41ZtAt9ImjyzR7wyJk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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