SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5302f199c2c032410b44b8c1f814041ffb7499a9fe2b4bf2d964036074cf45d8' 
  AND token = 'BVzxgkYo2CTHhkx+RJ25qMwHilI9fW/KUPL5P4MZ1J8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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