SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c3e7c31cba49a64747ac12d238f34c00dc1360256eb9bf7618fd70294a97a6a' 
  AND token = 'xUJIBviD9zPIsuQJcdvkZ97BAZQGoopFp7y+ZWJ8IZQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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