SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b589e86441d05d50465ccc10bae50ba1684a25c54af039a108b6f794814afa94' 
  AND token = 'TzJMzSIn2hOlovEQLTcxpqNvjmYcfKx6dQwCN03CTVM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}