SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6e8b95502c6453fc40b4912fe4a14c128532391682d83fd25ccb5bdbff892cd' 
  AND token = 'G4a2OVgc9Pswf3b4m9fXxAbGrcZpzJ3ltWON9Botop0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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