SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7d712ea6ee6001bf7758484a447493c32e50d7bfcd5384638a31028d6fe336b8' 
  AND token = 'IcQJnROYNdP7+yDplKMheWEWpYRVlmJphwpBp+yQ5hM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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