SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd139e3a1f9998da7928312e284a5056362a6053e7e0c8ad2ebfa22a5bbed4f66' 
  AND token = 'Z2hX2nhyu52DQPkfAhi3MrOTxSZrxRbepsFKmOghQtY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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