SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3bf5497da451ce351d481fdf0622949620f3d34447e1227b36da4cb482742d4' 
  AND token = '97ngQJRw9+mCcl/bO9S2weC/6Y8T7GAZNUjMhfVqpqw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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