SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '884cc1cb7c83180e289c1ac7f5da975d6c539bccca4507769dbd35f56c8abc38' 
  AND token = 'UJxiZcnDe7mc2CnmeZvuukurneBWfIFrR44NqYoHLdg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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